To double over or not arguement regularly comes up and I have yet to see a definitive answer. From experience of taking sockets off mostly installed by professionals I would say the majority I have done have not been doubled with the exception of the CPC which I have come across regularly.

Personally I do not double over in case sometime in the future a spur needs to be added. I do tend to use known makes eg MK and have yet to experience any problems of wires not being grabbed in sockets. The last time I had a loose wire was in a wall switch which was a no name make my SiL bought.

So I would really like to know what the current professional opinion is on the subject?

Richard