No, they don't forget it. AFAIK the problem is that most GPs don't actually have any basic First Aid training. I'm a member of a St. John Ambulance unit at university, and the medical students that are members of our unit say the only First Aid training they receive is as a SJA member. So otherwise when they graduate they know how to do all sorts of clever diagnoses and prescribe drugs for this that or the other but don't know how to do any basic lifesaving First Aid.