 Construction work began on the castle at some point between 1538 and 1540 , under the direction of a member of the local Cornish gentry , Thomas Treffry . By 1540 , a map of the local defences described the castle as only " half @-@ made " ; when the antiquarian John Leland visited what he described as a blockhouse in 1542 , he was hosted by Treffry , and afterwards recorded that the construction had been funded partly by Treffry and partly by the local town . 
