In this series, Laurence Llewellyn-Bowen visits some of the finest houses in Wales, stepping back in time to uncover their hidden stories. Today he's at Cresselly - a huge Georgian mansion in Pembrokeshire in which the Allen family have lived for the past 300 years. Laurence discovers the house was built with proceeds of St Anne's lighthouse and where a former resident would climb a rope to reach his bedroom every night.