Mystery of the drive behind unusual sexual desires

Sigmund Freud's research into defence mechanisms identified one, displacement, as the redirection of an impulse on to a substitute target. An individual who is uncomfortable with their desire for a real person may therefore substitute a fetish.

Academics consistently report the lack of evidence available to accurately study fetishism, adding that this is not helped by the sheer variety which exists.

Retired psychologist Alexander Wedderburn said he has never been able to come to a conclusion to what drives people towards fetishes, but said he believes many people arrive there naturally through boredom. He said: "Proper bondage, domination, sadism and masochism seems to me to be highly ethical and have pretty strict rules about nobody doing anything they don't want to.

"I think the internet makes this sort of thing easier to explore for the average citizen. Whether that means it will grow or not, I don't know, it probably will."