I have been given about a dozen or so of these. I am keen to use them temporarily to save some cash and then maybe upgrade later. But the plates are a different design to the standard ones and I would be keen to know if I need some sort of special back box or do they just fit a standard one? ie I wont use them if they need a special back box. thanks

Normal back box, BUT flush switches need a bit more depth inside the back box.  So what do you have ?  If you have the slim 16mm light switch boxes (I would never fit them) you might well struggle for enough room.  25mm or even 35mm deep boxes and there should be no problem.

Great thanks Dave - not bought the boxes yet so good to know I can use these if I fit deep boxes - thanks,.