Saltwood Castle Saltwood Castle is a castle in Saltwood village — which derives its name from the castle — 1 mile ( 2 km ) north of Hythe , Kent , England . The castle is known as the site where the plot was hatched to assassinate Thomas Becket ( 1118 – 1170 ) . More recently , it became the home of the art historian Lord Clark of Saltwood ( 1903 – 1983 ) , then his son Alan Clark ( 1928 – 1999 ) , a minister in Margaret Thatcher ' s government . History . Origins . The castle was probably erected on a Roman site , though Bronze Age implements and copper ingots discovered in Hayne ' s Wood , 1874 , show the site had already long been inhabited . The castle ' s website traces its history back to 488 CE , when Aesc , the son of Hengist and the King of Kent , built a castle on the site . It first appears , however , on a charter of King Egbert in 833 . The manor of Saltwood was granted to the priory of Christ Church in Canterbury by a deed dated 1026 . Under William the Conqueror , Saltwood , held by the Archbishop of Canterbury and let , under knights ’ service , to Hugo de Montfort , formed part of the string of large fiefs granted from Hithe to the New Forest , along the south coast of England . The structure was replaced by a twelfth - century Norman structure , with work extending over the next two centuries . It became home for a period to Henry d ' Essex , constable of England . Becket . Thomas Becket had asked Henry II on behalf of the Church for the restoration of the castle as an ecclesiastical palace . Henry instead gave it to one of his loyal barons named Ranulf de Broc . This leads to the implication that some complicity was possible in the murder of Becket by the baron Ranulf de Broc . It was during this time at Saltwood , on December 28 , 1170 , that four knights are presumed to have plotted the death of Becket , which took place the following day at Canterbury Cathedral , about 15 miles ( 24 km ) away . Hugh de Moreville was one of the four knights that committed the assassination , along with Reginald Fitzurse , William de Tracey , and Richard le Breton . After Becket ' s assassination , the castle was returned to the control of the archbishop of Canterbury . Gun - ports in the gatehouse that date to the period 1385 - 94 are attributed to Henry Yevele ( fl . 1353 - 1400 ) , called the " English father of the science of artillery fortification " by B . H . St John O ' Neil . A fourteenth - century chip - carved chest with arcading and rosettes along the front , with a later panelled top , formerly in the parish church , was reputed to have come originally from Saltwood Castle . The Wycliffite William Thorpe ' s account of his interrogation at Saltwood in 1407 is a familiar document because it was published by sixteenth - century Reformers . Recent history . Saltwood remained a church property until the reign of Henry VIII when Hythe and Saltwood were seized by the Crown . It became uninhabitable as the result of the earthquake of 6 April 1580 , but was restored in the nineteenth century , as a residence once again of the Archbishop of Canterbury . The gatehouse has been used as a residence ever since . During World War II , Nazi Hermann Göring ordered the Luftwaffe not to bomb Hythe , as he had designated Saltwood as his post - invasion home . The castle was the childhood home of Bill Deedes and was purchased in 1955 by Kenneth Clark , whose son Alan Clark subsequently lived there . After Alan Clark ' s death he was buried in the castle grounds , which remains in the Clark family today .