Hello all.. Just wanted to let you know about a bargain! I wouldn't usually buy from e-bay, but you cant really go wrong with a metal back box. 100 Flush Single Metal Back Boxes 16mm 25mm 35mm 47mm 1 Gang Electrical Pattress - https://www.ebay.co.uk/itm/100-Flush-Single-Metal-Back-Boxes-16mm-25mm-35mm-47mm-1-Gang-Electrical-Pattress/281062895771?ssPageName=STRK%3AMEBIDX%3AIT&var=580178846308&_trksid=p2057872.m2749.l2649 I ordered 100 x 16mm metal back boxes for £5.99. They have just arrived and they even have the oval grommet fitted to each of them. I realise we don't use them that much but I expect I'll still get through them before I retire . 6p each... surely no one can beat that!