I have lived in the Greater London area all my life. I have never heard of this before. I have not read about it in newspapers, nor has it been mentioned on local news channels. I do not believe it is widespread at all. I think as some scams become well known and well publicised, criminals have to think of new methods to fleece the unwary. It does, of course, depend how successful the new scams are. I do not believe this one will be very successful. I cannot imagine anyone being stupid enough to hand over money in the belief that this person can prevent a plane crash, or similar. If they could prevent such things, they would be employed by the aviation industry and be paid millions. I can understand someone handing over cash through fear - if they are genuinely afraid of this person. But in that case, the "scam" becomes irrelevant and it's just threatening behaviour.
Garry