Quote Originally Posted by Andrew Millne View Post
You may also find these of use, may save you a bit of work.

http://www.screwfix.com/prods/28261/...Spacer%20White
I agree. I had this issue in my house and I decided for the really shallow backboxes just to use the spacers - they have to be cut with a jigsaw to fit properly though.

http://nodeone.blogspot.com/2008/01/16mm-backboxes.html