thought i'd seen most of the stupid things they do, but this one is a doozy. having replaced a faulty double socket ( chrome) in a kitchen, taken a Zs of 1.1 ohms, thought to compare with another chrome socket 3m away. plugged in MFT and immediate error, confirmed as no earth by socket tester. so, isolated at CU, came to remove socket front and noticed only 1 faceplate screw in it. removed the 1 remaining screw to find the cpc.s had been removed from the terminal and wedged between the ceramic splashback and the back box. the sliding lug was also missing. it would seem that the kitchen fitter had done this to stop the cpc's ( which were both in 1 sleeve) from pushing the faceplate forward on the side with the missing lug and screw. fixed it properly in 10 minutes. still can't believe he could be that stupid.