We had a sparky round this afternoon to wire up a new light and a couple of sockets. As part of his checks he wanted to see whether the gas supply and water supply were earthed. He found the earth on the water, which needs to be renewed, but can't find the gas earth anywhere. So we need to get it sorted. We've been in the house for 5 years, and have a certificate from the previous owner from 2010 when the consumer unit was replaced to say all checks had been done and the earths were present. The gas one clearly wasn't. Is it worth going back to the electrician who did the work 8 years ago, or has too much time passed?