"It is the action of a peeping tom. In our country we prosecute peeping toms. That is exactly what they have done and they have been peeping with long lenses from a long way away. They are very distasteful." So said Sir John Major when he appeared on the Andrew Marr Show on Sunday, talking about those pictures of Kate, and the decision made by the Duke and Duchess of Cambridge to file a request in France for a criminal investigation into the photographer who took the offending photos.

It's not clear which offence Major was thinking of here. In the period since he left office, over 3000 new offences have appeared on the statute book. The crime of being a peeping tom is not, however, one of them. The Sexual Offences Act 2003 did introduce an offence of voyeurism to address a lacuna in the criminal law. This prevents a person from observing or recording a person doing a private act. Under UK law, however, the prosecution have to prove that it was for that person’s own, or in the case of recordings, another person’s sexual gratification.

Understandably perhaps, the offending photographer is lying low: the complaint lodged by the royals is against an unknown person. Speculation on his or her whereabouts leads to some interesting legal problems: if the photographer has, for example, left France and come to the UK, the question of whether we do in fact prosecute peeping toms would become all important. Could the CPS bring a prosecution in this country? Given that the pictures were taken in France, it would appear that there would be no jurisdiction to do so. That being so, could France seek to extradite the photographer if he has come to the UK? Under the Extradition Act 2003, a person may only be extradited for offences that are specified in a list, or for conduct which would amount to an offence in this country and is punishable with a prison sentence of at least 12 months. The answer then would depend on whether a court could be persuaded that had the pictures been taken here, his peeping tom conduct would have constituted an offence. As the law currently stands, that seems doubtful.