In message , Steve Firth writes
Last year I helped a friend replace her kitchen cupboards. When we took down one of them there was a neatly drilled hole in the plaster behind it with no rawl plug in it but with some very nice and quite artistic black scorch lines radiating from it for about 1/2" all around and a pencilled note saying "do not use"! It must have been interesting to observe! It was also directly above a 13A twin outlet that was still in use, after digging a hole in the plaster it was clear that the live had been neatly cut. The circuit had been used for years with a break in the live side. Oh and there were only wired fuses in a very overloaded and similarly blackened CU which has now been replaced with a new split load one.
Darwin must love DIYers.