John Trevanion Purnell Bettesworth - Trevanion (1780–1840) inherited Caerhays Castle from his father, rebuilding it in a gothic style. 

                                                                                                                 
The expensive works led to his financial ruin and he fled to France and then Belgium to avoid the stigma of bankruptcy.

Born at St Michael Caerhays, he was the eldest son of John Bettesworth and was educated at Winchester College and Eton College. Appointed High Sheriff of Cornwall in 1804 he served as Member of Parliament for Penryn in 1807.  His tenure must be one of the shortest ever. 

Contesting the seat at 1806 general election he was defeated by Sir Christopher Hawkins (April 6^th) but the electoral result was overturned in  February 1807, due to electoral fraud and he held the seat until the general election in May 1807, in other words for a mere three months.  He was also Lieutenant Colonel in the Reserve Cornwall militia, which was formed to defend the Cornish coast in the event of the feared French invasion.   On receiving his inheritance, Bettesworth-Trevanion employed John Nash to rebuild Caerhays. 

Construction began in 1807 and when finished three years later, Bettesworth-Trevanion was financially ruined and fled to Paris.  He died in Brussels in 1840.