Smear Evo-Stik or Bostik on both surfaces.Would it stick firmly to a backing board though? Wouldn’t want it to come off when things were plugged in or unplugged!
Allow to become tack dry then carefully align with the back board and press firmly. You will pull the plaster off the wall before the socket comes off the board. (But as the board will be screwed to the wall, that ain't gonna happen either.