Tart cards are the means by which many London prostitutes advertise their services. Step into almost any central London phone box and you can contemplate up to 80 cards inviting you to be tied, teased, spanked or massaged.

Even if a police crackdown, the internet and the increasing use of mobile phones suggest their days are numbered, tart cards are still so pervasive they are now regarded as items of accidental art and have something of a cult following...