A frend of mine has recently had some building work done. She gave a contract to a builder who has sorted out all the eletric plumbing plastering etc. now with regards to the plumbing work he employed a plumber to do the work. the plumber him self was gas safe redge but he had a guy at his firm who wasnt gas safe do all the work. He then checked every thing and commisioned it after and signed it off. Evereything seems to be of a good standard but there must be a line where the gas safe plumber must have had to worked on the system and cant just turn up and sign it off?