Mail fraud in the UK

Is there a British equivalent to the US Postal Inspector? That is, an office which deals specifically with mail fraud?

The reason I ask is that the non-profit organization I work for has learned that someone else has rented a London P.O. Box and is now advertizing it as our address. I’m not sure if this counts as mail fraud or not, and whether there is anything we can do about it.

PO Boxes are controlled by the Royal Mail, so I’d start off with contacting them about possible fraud: http://www.royalmail.com/portal/rm/content1?catId=600006&mediaId=600043

Next port of call is Postcomm, the government regulator, although I think the best they can do is point you in further directions. I suspect it’ll be a case for the Metropolitan Police, and that this would be through contacting the Royal Mail.

Royal Mail has a postal Fraud department: Call them on +44 (0)207 2396 655.

You could also try contacting Trading Standards - the Government department that deals with protecting the public from fraudulent practices: http://www.tradingstandards.gov.uk/

Another thought - if the organisation is registered as a charity in the UK, then the Charity Commission is someone else to contact: http://www.charity-commission.gov.uk/