From an article in Mr. which suggests that Britons, and Londoners in particular, were fornicating all over our parks and streets. A lovely thought but I think Billy Graham, who claimed that he and his wife, "saw two couples in the midst of the sex act in broad daylight", may well have been fantasising.
The article then goes on to establish the historical sexiness of the city by apparently quoting an 1857 issue of The Lancet which claimed that one in every 60 London houses was a brothel and one of every 16 females of all ages a whore.
My favourite part, though, states, "in a recent study called English Life and Leisure...it would seem that, as in America, the so-called 'charity girl', who copulates for free, has severely cut into the ranks of her more professional sisters".

From Mr., Vol.1 No.11 1959.Vintage Scans Mid-Century Advertising, Strumpetry & Design