And nearly half have done illicit "sexting" - sending naughty messages or phone texts to someone other than their partner, and thirty-five per cent have included sleazy photos of themselves, reports The Sun.
The survey of 2,000 people for TV show Sex Rehab, launched tonight on UKTV channel Really, found 46 per cent of those questioned exchanged explicit secret messages.
A third watched porn online, with one in three saying they were addicted - without their partners realising, and one in five had made their own sex tape.
The Big Sex Survey found the average Brit has sex 6,552 times in their life, with the average session lasting 20 minutes.
It claims 14 million have done it in public places, with a third romping in shopping centres, toilets or outdoors. Half admitted using sex toys, and three per cent of men confessed to having a sex doll.