For starters, many of the capital’s ultra-high net worth residents have been lightly prepping for decades. “I had one eccentric client who had a nuclear shelter built under any property he bought, fully equipped with food, water, filtered air and so on,” says luxury estate agent Trevor Abrahmsohn of Glentree Estates. “A number of mansions and super-mansions have basements and sub basements lying 30-40 feet underground. These might ostensibly be used as a cinema, a gym — I even have a client who has a subterranean ballroom — but they are also going to be much safer in the unlikely event of a nuclear attack, for example.”