Have you noticed how many are around? I had four pounds change today at a gas station and two of them were slugs! I read an article some time ago about the high percentage of fake quids around but it does seem that it is a high percentage, I've had loads.
Check your change now, I bet everyone has at least one, they are easy to spot as the knurling around the edge is usually very poor as are the images and they are just poor all over really, it looks like the police are beaten on this one.
When I gave them back to the assistant at the gas station, he just gave me two more and tossed the slugs back in the till, so some other poor sod will get them, who cares?
Al

