The castle was built soon after the Norman Conquest by William de Warenne, the Earl of Surrey, at the intersection of the River Nar and the Peddars Way.

[3] Acre was already an Anglo-Saxon estate centre and at the time of the invasion was owned by a wealthy man called Toki, but he was quickly replaced by Frederick, a Flemish lord and William's brother-in-law.

[4] When Frederick died around 1070, William acquired control of the manor, which formed part of his massive land holdings across the region.

[5] The castle was strategically located where the River Nar met the Peddars Way, an old Roman road, at the centre of Warenne's other estates in Norfolk, and may have been built on top of Toki's former house.

[9][b] William gave St Mary's, the former parish church which was now surrounded by the castle's outer bailey, to the Cluniac order of monks, along with 110 hectares (270 acres) of farmland.

He was exiled and disseised of his English estates, including Castle Acre, until in 1103 the duke was able to persuade Henry to permit William to return and reclaim his lands.

[17] There was fighting across much of the country, although less so in Norfolk, but William also faced challenges to his preeminence in the region from the growing power of the d'Albinis and de Vere families.

[25] It had previously run straight across the de Warenne estates, but it was now diverted so that travellers coming from the south had to leave the main road, progress west around the priory and the castle fishpond, before reaching the southern end of the walled town and the route to the north.

[26] The route was designed to highlight the important symbols of the de Warenne lordship of the region and provide a dramatic view of the castle, and may have been a response to the political uncertainties of the Anarchy years.

In 1153, however, Stephen faced a military stalemate in the civil war and agreed that Matilda's son, the future Henry II, should inherit the throne on his death, rather than William of Blois.

[20] Hamelin changed the plan for the castle: the original ambition for the height of the keep was reduced and the southern half of the building was demolished.

[31] The seventh earl, John de Warenne, married Joan, the niece of Edward II, but the marriage failed and instead he chose to live with his mistress Maud Nereford.

[33] In 1316, John therefore gave Castle Acre to Aymer de Valence, the Earl of Pembroke and England's Ambassador to Rome, probably to encourage him to present a petition to the Pope to annul the marriage the following year.

[35] After 1537, Thomas Howard, the Duke of Norfolk, leased the ruins of the castle and the adjacent priory, which had been closed during the Dissolution of the Monasteries.

[38] Edward, who was interested in history and possibly keen to reinforce his own credentials as a new entrant to the English elite, carried out repairs to the castle at a cost of £60.

[36] The main entrance to the castle came from the town through the north-west corner of the outer bailey; this was defended by a stone gatehouse and a portcullis, of which only the foundations now survive.

[36] The inner bailey is reached by a bridge, which was originally made from wood, later rebuilt in stone, before replaced by the current steel version in the 20th century.