Trematon Castle Trematon Castle is situated near Saltash in Cornwall , United Kingdom . It is similar in style to the later Restormel Castle , with a 12th - century keep . Trematon Castle overlooks Plymouth Sound and was built probably by Robert , Count of Mortain on the ruins of an earlier Roman fort : it is a motte - and - bailey castle and dates from soon after the Norman conquest . It occupies a sentinel position one and a half miles south - east of Trematon village ( ) . Description . Trematon Castle , like Restormel Castle , has a stone keep raised on an earlier motte . Although in ruins , much of the Norman walls remain standing , so that the original form of the Castle and keep are clear . The keep is oval and has walls ten feet thick and thirty feet high . The internal diameter is approximately 21 metres . A rectangular gatehouse , built in 1270 , has two floors and a portcullis . Both are in good condition . The military historian Sir Charles Oman says of the castle ' s situation " Trematon is high aloft , on one of the summits of the rather chaotic group of hill - tops which lie behind Saltash and its daring modern bridge . " Within the Castle courtyard stands a Georgian house built in about 1808 . This has four reception rooms and six main bedrooms , as well as servants ' quarters . Part of the original Castle wall was demolished to give this house a view into the surrounding countryside . History . The castle was established here by Robert , Count of Mortain soon after the Norman Conquest . From the Conquest until 1270 , the rights for the ferry from Saltash Passage on the Plymouth side of the River Tamar to Saltash belonged to the Valletort family . When Roger de Valletort sold Trematon Castle and manor to Richard Earl of Cornwall , the rent was paid to the Earl ' s bailiff . In the thirteenth century , this amounted to nearly seven pounds sterling . The Castle has remained the property of the Earls and Dukes of Cornwall without interruption since 1270 , when Earl Richard bought it for £300 . When Sir Francis Drake returned from his circumnavigation voyage in 1580 , he came into harbour in Plymouth , then slipped out to anchor behind St Nicholas Island until word came from Queen Elizabeth ' s Court for the treasures he had gathered to be stored in Trematon Castle . The horde consisted of gold , silver , and precious stones , mainly emeralds , the result of piracy from Spanish ships along the west coast of South America . Before being moved for storage in the Tower of London , the treasure was temporarily stored in the " Golden Hinde " . In 1961 the Duchy of Cornwall advertised the Castle to be let on a full repairing lease for 21 years , with breaks , at a rent of £250 a year . It subsequently became the home in Cornwall of Hugh Foot , Lord Caradon , and his son Paul Foot , a campaigning journalist , spent some of his youth there . Lord Caradon ' s brother Michael Foot , the leader of the Labour Party from 1980 – 1983 , was a frequent visitor to the castle . Queen Elizabeth II visited the Castle on 25 July 1962 accompanied by the Lord Lieutenant of Cornwall , Sir Edward Bolitho , before driving to Fowey and embarking in HMY Britannia . The castle is currently closed to the public . Manor of Trematon . Trematon appears in the Domesday Book ( 1086 ) as the manor of " Tremetone " . The manor was one of the 17 Antiqua maneria of the Duchy of Cornwall . Feet of Fines for Cornwall A . D . 1272 - 1307 . " Feet of Fines were final judgements regarding land after legal action had been taken . They provided a record of title , often after purchase . " The Manor and Castle of Trematon was the cause of a court case on 16 February 1270 . Richard Plantagenet ( created Earl of Cornwall 1226 ) , the son of King John of England , was the claimant and Roger de Valle Torta the opponent regarding this land , 60½ knights fees in Devon and Cornwall , and the Manor of Calstock . The land was said to " be the right of the said king as those which he had by Roger ' s gift . " Following the endorsement of this foot of fine it says : " And Henry de la Pomerai and Peter Corbet put in their claim . This was saying that they did not agree with this decision and were lodging notice of their rights to the land . The argument was to continue for many years . " Additional details appear in the " Fine Rolls Vol . 1 1272 - 1307 " order : In 1274 , the executors of Thomas ' will were ordered to deliver to Peter Corbet , son and heir of Thomas Corbet , deceased , the lands which had belonged to his father . Peter was born in 1298 , the son of Thomas , who died in 1300 , and his first wife , Joan Mortimer . A page note in the Feet of Fines confirms that Peter Corbet was the grandson of Isabella Corbet ( formerly Valletort ) . This Peter , in 1315 , was to petition Parliament for the recovery of the Trematon estate , alleging that when Roger de Valletort made a deed of gift in favour of Richard , Earl of Cornwall , he was " non compos mentis " .