tdziemia
Would this have been the Wilton Castle in Herefordshire: https://en.wikipedia.org/wiki/Wilton_Castle
… or Wilton in Wiltshire? (your Wiki link)
A bit confusing since th term “Wilton Castle” is used in the reference you linked.
It appears Wilton Castle in whiltshire ! Although alot of references just say wilton, the British Museum stays Wilton/Wilton Castle on entries. There was definitely a mint at whilshire: Wilton: Town of Mints, Saints and Carpets