They are made for grid switches but just as easy and cheaper to use these - http://www.tlc-direct.co.uk/Technical/DataSheets/MK/PlateSwitches.pdf you want the K5207 WHI
BTW the K5207 has two switches, one has "sink" & "bath" written on it. I guess this isn't the one you meant?
http://www.fastlec.co.uk/mk-dual-switch-20a-with-neon-k5207-whi-p-10842.html