On the Monopoly board, Mayfair is London’s most expensive property. Its streets are lined with grand townhouses, embassies and ambassadors’ residences standing shoulder-to-shoulder with some of Britain’s fanciest hotels and restaurants.

But beneath this outward appearance of splendour, a crime wave has taken hold. Violence and anti-social behaviour are causing distress and alarm to wealthier residents. There are daily reports of robberies and muggings, while wilder claims – which have proved to be false – of multiple homicides abound, only heightening the tension.

Added to the concern is a large, temporary encampment on Park Lane – Mayfair’s Monopoly twin – of Romanians and Bulgarians, who have been able to resist deportation thanks to a favourable High Court ruling.

Men, women and children sleep rough in tents or on cardboard mattresses, accused of being troublesome beggars and of being behind some petty thefts and pickpocketing.

Last week, The Daily Telegraph witnessed police and council officials clearing them from a campsite in an early-morning raid.