Not mandatory, as it turns out - just ubiquitous. You can get similar sockets with no switch if you want them never to be turned off: https://www.edwardes.co.u

Not mandatory, as it turns out - just ubiquitous. You can get similar sockets with no switch if you want them never to be turned off: https://www.edwardes.co.uk/products/mk-k781whi-2-gang-13-amp-un-switched-white-socket-outlet https://www.edwardes.co.uk/products/mk-k781whi-2-gang-13-amp...