I'm all for doing compliant jobs but 12 Months ago loads of circuits would be fitted with no RCD's and no-one was even in the slightest bit concerned. I realise this is about fitting to the 17th edition and whether it should or shouldn;t have been and who is responsible if something goes wrong, but if someone else fitted a 16th edition board then that's down to them, can;t see anything that makes it unsafe or dangerous, just that if something happens then they need to explain their actions. Wouldn;t bother me too much if I came across a 16th edition board, my own 16th edition boards at home are staying as they are.