In medieval and Early Modern England, Wales and Ireland, a deer park (Latin : novale cervorum, campus cervorum) was an enclosed area containing deer. It was bounded by a ditch and bank with a wooden park pale on top of the bank, or by a stone or brick wall.  The ditch was on the inside  increasing the effective height. Some parks had deer "leaps", where there was an external ramp and the inner ditch was constructed on a grander scale, thus allowing deer to enter the park but preventing them from leaving. 
Some deer parks were established in the Anglo-Saxon era and are mentioned in Anglo-Saxon Charters; these were often called hays (from Old English heġe (“hedge, fence”) and ġehæġ (“an enclosed piece of land”).  
After the Norman conquest of England in 1066 William the Conqueror seized existing game reserves. Deer parks flourished and proliferated under the Normans,  forming a forerunner of the deer parks that became popular among England's landed gentry. The Domesday Book of 1086 records thirty-six of them.
Initially the Norman kings maintained an exclusive right to keep and hunt deer and established forest law for this purpose.  In due course they also allowed members of the nobility and senior clergy to maintain deer parks. At their peak at the turn of the 14th century, deer parks may have covered 2% of the land area of England. 
After the Norman conquest of Ireland in 1169 many deer parks were established in the new Lordship of Ireland.  The fallow deer is not native to Ireland and is believed to have been introduced at the royal deer park at Glencree in 1244. The Cambro-Norman landlords also used deer parks to produce timber and charcoal, and to protect their livestock (cattle, sheep, etc.) from being stolen by the native Gaelic Irish. Research by Fiona Beglane identified forty-six Irish deer parks established before 1400. 
James I was an enthusiast for hunting but it became less fashionable and popular after the Civil War. The number of deer parks then declined, contemporary books documenting other more profitable uses for such an estate.  During the 18th century many deer parks were landscaped, where deer then became optional within larger country parks, several of which were created or enlarged from wealth from trade and colonization in the British Empire. These later mostly gave way to profitable agriculture dependent on crop prices, with large parts of the workforce having been attracted elsewhere following increasing industrialization. This created pressure to sell off parts or divide such estates while rural population growth pushed up poor law rates (particularly outdoor relief and the Labour Rate) and urban poverty led to the introduction of lump sum capital taxation such as inheritance tax and a shift in power away from the aristocracy. 
Deer parks are notable landscape features in their own right. However, where they have survived into the 20th century, the lack of ploughing or development has often preserved other features within the park,  including barrows (tumuli), Roman roads and abandoned villages.
John Norden wrote of Cornish deer parks that the Arundells had the 'stateliest park' in the shire. 
To establish a deer park a royal licence was required, known as a "licence to empark"  —especially if the park was in or near a royal forest. Because of their cost and exclusivity, deer parks became status symbols. Deer were almost all kept within exclusive reserves with the larger ones often used as aristocratic playgrounds, for hunting, often with deer being driven into nets; and, there was no legitimate market for venison without an established provenance.  Thus the ability to eat venison or give it to others was also a status symbol. Consequently, many deer parks were maintained for the supply of venison, rather than hunting the deer. Small deer parks which functioned primarily as household larders were attached to many smaller manors, such as at Umberleigh in Devon.  Owners would grant to their friends or to others to whom they owed a favour, a signed warrant for a specified number of deer, usually one only, specified as buck or doe, which the recipient would present to the park keeper who would select and kill one and hand the carcass to the grantee. The Lisle Papers dating from the 1530s contains many such letters from prospective grantees requesting such gifts from the park of Honor Grenville, the lady of the manor of Umberleigh in Devon, and also contains reports to her from her bailiff listing grants of venison made from her park during the past year.  Such grants acted as common features of the mediaeval social machinery.
King Henry VIII appointed Sir William Denys (1470–1533) an Esquire of the Body at some date before 5 June 1511. It was perhaps at the very time of William's appointment to that position at court that the King promised him the honour of a licence to empark 500 acres of his manor of Dyrham in Gloucestershire, which is to say to enclose the land with a wall or hedgebank and to establish a captive herd of deer within, with exclusive hunting rights. This grant is witnessed by a charter on parchment, to which is affixed a rare example of a perfect great seal of Henry VIII, now hanging in a frame beneath the main staircase of Dyrham Park. It clearly was handed down with the deeds of the manor on the termination of the Denys era at Dyrham. The charter is of exceptional interest as it is signed as witnesses by men of the greatest importance in the state, who were at the King's side at that moment, at the Palace of Westminster. The text of the document, translated from Latin is as follows: 
Henry by the grace of God King of England and France and Lord of Ireland sends greetings to his archbishops, bishops, abbotts, priors, dukes, marquises, earls, barons, judges, sheriffs, reeves, ministers and all our bailiffs and faithful subjects. Let it be known that we, motivated by our especial grace and certain knowledge of him, have granted for us and our heirs to our faithful servant William Denys, esquire of the Royal Body, to him, his heirs and assigns, the right to empark 500 acres of land, meadow, pasture and wood together with appurtenance at Le Worthy within the manor of Dereham in the county of Gloucestershire and enclose them with fences and hedges in order to make a park there. Also that they may have free warren in all their demesne lands within the said manor. No other person may enter this park or warren to hunt or catch anything which might belong to that park or warren without permission from William, his heirs or assigns under penalty of £10, provided that the land is not within our forest.
- The most reverend in Christ father William Canterbury our chancellor and archbishop
- The reverend in Christ fathers Richard Winchester, Keeper of the Privy Purse and
- Thomas Durham, our secretary, bishops.
- Thomas Surrey, Treasurer of England and
- George Shrewsbury, steward of our household, earls.
- Charles Somerset Lord Herbert, our chamberlain and
- George Neville of Abergavenny, barons.
- Thomas Lovell, treasurer of our household and
- Edward Poynings, comptroller of our household, knights, and many others.
Given by our hand at Westminster on the 5th day of June in the 3rd year of our reign. (1511)
From the size of the present park it appears that only about 250 acres were ultimately enclosed. The grant of emparkment was separate from and in addition to the grant of free warren in his demesne lands. This latter allowed him to hunt exclusively on his unemparked other untenanted lands which were managed by his own staff. High dry-stone walls, typical of Gloucestershire, still survive around parts of the present parkland, which is still stocked with a herd of fallow deer. The park was thus an area in which Denys's deer would be at his own disposal and would be safe from being hunted or otherwise taken by any other person, including his neighbours and the king himself. The king when on royal progress throughout his kingdom was accompanied by an enormous entourage which needed daily feeding and entertainment, both of which functions were achieved by holding driven game shoots, in which an area of ground several miles in area would be surrounded and any deer within would be driven towards a specified exit where the king and his favoured courtiers would be awaiting with bows and arrows to kill them. Thus several dozen if not hundreds of deer could be killed in a single day, to the impoverishment of the local countryside for several months if not years into the future.  Thus any landowner with a licensed park, even if within the circuit of such a drive, would be immune from the entry of such beaters into his park, and his deer would remain untouched.
The French ambassador Charles de Marillac in his despatch of 12 August 1541 described this process as King Henry VIII went on royal progress to York: The King’s fashion of proceeding in this progress is, wherever there are numerous deer, to enclose two to three hundred in the trees and then send in many greyhounds to kill them, that he may share them among the gentlemen of the country and of his court.  Deer situated within licensed deerparks were thus immune from such mass round-ups, and the grant by the king of such licences therefore had the effect of depriving himself of much valuable game with which to feed his followers.
Early historical records are replete with instances of noblemen breaking into each other's parks and killing deer therein, often as a result of a local territorial dispute or vendetta or merely from high spirits. The penalties inflicted by royal justice were severe in such instances. For example, in 1523 Sir William St Loe (d. 1556) of Sutton Court, Chew Magna, Somerset, together with 16 others, armed with bows and arrows, crossbows and swords, broke into Banwell Park in Somerset, attached to Banwell Abbey, a residence belonging to Bishop of Bath and Wells William Barlow, and killed 4 bucks and other deer. In the following August he made a similar raid and killed more than 20 deer, the heads of which he stuck on the boundary palings. He was ordered to appear before a magistrate, but the record of his punishment if any has not survived. However, after the Dissolution of the Monasteries a short while later, in 1552 Sir William obtained for himself from the crown the office of Keeper of Banwell Park. 
Deer parks could vary in size from a circumference of many miles down to what amounted to little more than a deer paddock.  The landscape within a deer park was manipulated to produce a habitat that was both suitable for the deer and also provided space for hunting. "Tree dotted lawns, tree clumps and compact woods"  provided "launds" (pasture)  over which the deer were hunted and wooded cover for the deer to avoid human contact. The landscape was intended to be visually attractive as well as functional.
W. G. Hoskins remarked that "the reconstruction of medieval parks and their boundaries is one of the many useful tasks awaiting the field-worker with patience and a good local knowledge".  Most deer parks were bounded by significant earthworks topped by a park pale, typically of cleft oak stakes.  These boundaries typically have a curving, rounded plan, possibly to economise on the materials and work involved in fencing  and ditching.
A few deer parks in areas with plentiful building stone had stone walls instead of a park pale.  Examples include Barnsdale in Yorkshire and Burghley on the Cambridgeshire/Lincolnshire border. 
Boundary earthworks have survived "in considerable numbers and a good state of preservation".  Even where the bank and ditch do not survive, their former course can sometimes still be traced in modern field boundaries.  The boundaries of early deer parks often formed parish boundaries. Where the deer park reverted to agriculture, the newly established field system was often rectilinear, clearly contrasting with the system outside the park.
In Ireland, the placename Deerpark is common, but it is post-medieval in origin and does not indicate a Norman-era deer park.  Ireland's best-known deerpark, for example, is the Phoenix Park, but that was not stocked with deer until 1662. 
Ashdown Forest is an ancient area of open heathland occupying the highest sandy ridge-top of the High Weald Area of Outstanding Natural Beauty. It is situated some 30 miles (48 km) south of London in the county of East Sussex, England. Rising to an elevation of 732 feet (223 m) above sea level, its heights provide expansive vistas across the heavily wooded hills of the Weald to the chalk escarpments of the North Downs and South Downs on the horizon.
Epping Forest is a 2,400-hectare (5,900-acre) area of ancient woodland, and other established habitats, which straddles the border between Greater London and Essex. The main body of the forest stretches from Epping in the north, to Chingford on the edge of the London built-up area. South of Chingford the forest narrows, and forms a green corridor that extends deep into East London, as far as Forest Gate; the Forest's position gives rise to its nickname, the Cockney Paradise. It is the largest forest in London.
A royal forest, occasionally known as a kingswood, is an area of land with different definitions in England, Wales, Scotland and Ireland. The term forest in the ordinary modern understanding refers to an area of wooded land; however, the original medieval sense was closer to the modern idea of a "preserve" – i.e. land legally set aside for specific purposes such as royal hunting – with less emphasis on its composition. There are also differing and contextual interpretations in Continental Europe derived from the Carolingian and Merovingian legal systems.
Verderers are forestry officials in England who deal with common land in certain former royal hunting areas which are the property of the Crown. The office was developed in the Middle Ages to administer forest law on behalf of the King. Verderers investigated and recorded minor offences such as the taking of venison and the illegal cutting of woodland, and dealt with the day-to-day forest administration. In the modern era, verderers are still to be found in the New Forest, the Forest of Dean, and Epping Forest, where they serve to protect commoning practices, and conserve the traditional landscape and wildlife.
Duffield Frith was, in medieval times, an area of Derbyshire in England, part of that bestowed upon Henry de Ferrers by King William, controlled from his seat at Duffield Castle. From 1266 it became part of the Duchy of Lancaster and from 1285 it was a Royal Forest with its own Forest Courts.
Wychwood or Wychwood Forest is a 501.7-hectare (1,240-acre) biological Site of Special Scientific Interest north of Witney in Oxfordshire. It is also a Nature Conservation Review site, Grade 1, and an area of 263.4 hectares is a national nature reserve The site contains a long barrow dating to the Neolithic period, which is a scheduled monument.
Pucklechurch is a large village and civil parish in South Gloucestershire, England. It has a current population of about 3000. The village dates back over a thousand years and was once the site of a royal hunting lodge, as it adjoined a large forest.
Siston is a small village in South Gloucestershire, England. It is 7 miles (11 km) east of Bristol at the confluence of the two sources of the Siston Brook, a tributary of the River Avon. The village consists of a number of cottages and farms centred on St Anne's Church, and the grand Tudor manor house of Siston Court. Anciently it was bordered to the west by the royal Hunting Forest of Kingswood, stretching westward most of the way to Bristol Castle, always a royal possession, caput of the Forest. The local part of the disafforested Kingswood became Siston Common but has recently been eroded by the construction of the Avon Ring Road and housing developments. In 1989 the village and environs were classed as a conservation area and thus have statutory protection from overdevelopment.
Ashbury is a village and large civil parish at the upper end (west) of the Vale of White Horse. It was part of Berkshire until the 1974 boundary changes transferred it to Oxfordshire. The village is centred 7 miles (11 km) east of Swindon in neighbouring Wiltshire. The parish includes the hamlets of Idstone and Kingstone Winslow. The 2011 Census recorded the parish's population as 506.
Dyrham Park is a baroque English country house in an ancient deer park near the village of Dyrham in South Gloucestershire, England. The house, with the attached orangery and stable block is a Grade I listed building, while the park is Grade II* listed on the National Register of Historic Parks and Gardens.
Chapelizod is a village preserved within the city of Dublin, Ireland. It lies in the wooded valley of the River Liffey, near the Strawberry Beds and the Phoenix Park. The village is associated with Iseult of Ireland and the location of Iseult's chapel. Chapelizod is under the administration of Dublin City Council.
King's Somborne is a village in Hampshire, England. The village lies on the edge of the valley of the River Test.
Hatfield Forest is a 403.2-hectare (996-acre) biological Site of Special Scientific Interest in Essex, three miles east of Bishop's Stortford. It is also a National Nature Reserve and a Nature Conservation Review site. It is owned and managed by the National Trust. A medieval warren in the forest is a Scheduled Monument.
Ashdown House is a 17th-century country house in the civil parish of Ashbury in the English county of Oxfordshire. Until 1974 the house was in the county of Berkshire, and the nearby village of Lambourn remains in that county.
The Charter of the Forest of 1217 is a charter that re-established for free men rights of access to the royal forest that had been eroded by King William the Conqueror and his heirs. Many of its provisions were in force for centuries afterwards. It was originally sealed in England by the young King Henry III, acting under the regency of William Marshal, 1st Earl of Pembroke.
Feckenham Forest was a royal forest, centred on the village of Feckenham, covering large parts of Worcestershire and west Warwickshire. It was not entirely wooded, nor entirely the property of the King. Rather, the King had legal rights over game, wood and grazing within the forest, and special courts imposed harsh penalties when these rights were violated. Courts and the forest gaol were located at Feckenham and executions took place at Gallows Green near Hanbury.
Sir William Denys of Dyrham, Gloucestershire, was a courtier of King Henry VIII and High Sheriff of Gloucestershire in 1518 and 1526. The surname is sometimes transcribed as Dennis.
The Manor of Dyrham was a former manorial estate in the parish of Dyrham in South Gloucestershire, England.
A deer hay wind, deer fold or elrick is an artificial, natural or modified natural feature used in the culling, capture or management of deer in relation to deer parks or natural woodland and open countryside. These structures have existed for many centuries and after falling out of use and their function having been forgotten the more substantial earth or stone examples have attracted names such as Roman Trenches, Old Fortifications, etc. The hinds were the main target of the hunt.
Sir William le Deveneys was a Crown administrator and judge in late thirteenth and early fourteenth century Ireland, who was very briefly Chief Justice of the Irish Common Pleas.