Owners ordered to fill in illegal basement dug under 300-year old Mayfair house

The owners of a 300-year-old Georgian townhouse who dug a basement underneath it without permission have been told to fill it in again.The house, on Mayfair’s Park Street, is an early 18th-century townhouse built in the late 1720s that has survived largely intact, particularly the main interior levels. The current owners bought the house for just under £3 million in 2010 (so it is worth considerably more now) and shortly afterwards applied for planning permission to dig a second-leve