After the Norman Conquest of England in the 11th century, William de Mohun constructed a timber castle on the site as part of the pacification of Somerset.

[1][nb 1] During the early medieval period the sea reached the base of the hill, close to the mouth of the River Avill, offering a natural defence and making the village an inland port.

[4] This was built on the summit of the hill and was possibly intended to protect the region against sea-borne raiders; by the mid-11th century it was controlled by a local nobleman called Aelfric.

It was common in the period for the Normans to build religious houses to accompany major castles, and accordingly William de Mohun endowed a Benedictine priory at Dunster in 1090, along with its parent abbey at Bath.

[12] In the late 1130s England began to descend into a period of civil war known as the Anarchy, during which the supporters of King Stephen fought with those of the Empress Matilda for control of the kingdom.

[26][nb 5] The new entrance lay at right-angles to the old and was three storeys high, built of imported Bristol red sandstone, and contained extensive apartments; it formed a grand, if ill-defended, ceremonial route into the castle.

[30] Such a park would have been highly prestigious and allowed the Luttrells to engage in hunting, providing the castle with a supply of venison as well as generating income.

In 1461, Sir James Luttrell died following the Lancastrian defeat at the Second Battle of St Albans, and his family were deprived of their estates by the Yorkist Edward IV.

[32] Andrew's son Sir John Luttrell, who inherited the castle, was a famous soldier, diplomat, and courtier under Henry VIII and Edward VI, serving in France and in Scotland during the conflicts of the Rough Wooing.

Arnold was an important architect in the south-west of England, and had managed the building of nearby Montacute, Cranborne House and also Wadham College, Oxford.

[36][nb 6] When the First English Civil War began in August 1642, George's eldest son Thomas supported Parliament; William Russell, 1st Duke of Bedford and Parliamentarian commander in Devon and Somerset, ordered him to strengthen the garrison at Dunster.

[40] The local Royalist commander William Seymour, 2nd Duke of Somerset, attacked the castle in 1642 but was repulsed by the garrison, led by Thomas' wife Jane.

[41] In early 1643, the war in the south-west turned in favour of the King, and on 7 June 1643 the Royalists assaulted the castle again and Luttrell switched sides.

[42] During 1645 the Royalist military cause largely collapsed, and Colonel Robert Blake led a Parliamentarian force against Dunster in October.

[41] Dunster was briefly relieved in February 1646 but the siege resumed, and by April the Royalist position was untenable; Wyndham negotiated an honourable surrender and a Parliamentarian garrison installed.

[43] After the end of the Second English Civil War in 1649, Parliament decided to deliberately destroy, or slight, the defences of castles in key Royalist areas, including the south-west.

[46] George Luttrell died without children, and Dunster Castle passed to his brother Francis, who survived the political turmoil of the Commonwealth prior to the 1660 Stuart Restoration.

He married Mary Tregonwell, a wealthy heiress worth £2,500 a year, and used her income to modernise the castle during the 1680s, including a grand staircase in the latest style.

[51] A safer, if less grand, approach road to the castle was created, called the New Way, and the remains of the Upper Ward on top of the motte were flattened to be used as a bowling green, complete with an octagonal summer house.

[53] The couple redesigned and redecorated the castle in a Rococo style, including the extensive use of the recently invented and highly fashionable wallpaper.

[54] Henry Luttrell raised the ground height of the Lower Ward between 1764 and 1765 to extend the New Way all around to the front of his mansion, adding additional ornamental towers onto the inside of the Great Gatehouse in the process.

[65] The roof of the Great Gatehouse was raised to create a more uniform sequence of battlements, and a large hall for gatherings of the local farmers installed.

[69] As part of his work, Salvin appears to have used a number of rolled wrought-iron beams to span the resulting structural gaps in the building, an advanced use of that technology for the time.

This was the first time the National Trust have taken this approach to a Grade I listed building, and it is expected to save 1,714 kg (3,778 lb) of carbon a year.