Coxe incorrectly lists this as Caldenoch Castle. Galdenoch Castle was constructed in 1547 and was home of Gilbert Agnew of Lochnaw until 1570. According to the Galdenoch Castle Lodge website, "heavy fines imposed on the family for their support of the Covenanters and a failed attempt to establish salt pans on the coast nearby, left them in financial ruin at the end of the 17th century". Due to the ruinous state of the castle, it is not open to the public but can be viewed externally.
The building is associated with a bizarre, if not absurd, ghost story. Many years ago, the spectre in question took the tenant's grandmother down to the local burn, washed her and left her naked on the banks! It then boasted to the rest of the family about what it had done.
Galdenoch Castle,
Leswalt,
Stranraer,
DG9 0RS.
For further information, please read Haunted Britain by Antony D. Hippisley Coxe.