The General Medical Council is the body which by statute regulates the medical profession in the UK. Any member of the public may check whether someone purporting to be a doctor is qualified by checking their registration on-line on www.gmc-uk.org
So how accurate is the register? I today checked the registration of a doctor who died in April 2006 - fifteen months ago. Amazingly, he is still listed.
It was Fredrick Forsyth in Day of the Jackal who exposed the scam of getting a passport in the name of someone who had died. But it appears that the GMC still hasn't got round to closing the same loophole for fake doctors.