In article om,
" says...
Hello All

My tiler is having some problems cutting out a square in a 60x40
Travertine tile. This will fit around the thermostatic mixer. He
decided to just notch a rectangle out and fixed it after fixing the
main piece which I am not happy with as it doesn't look right.

That's the normal method of doing it.

Does anyone have any bright ideas on the easiest way to do this?
something I can suggest he trys. I'm assuming he has a normal electric
tile cutting machine, he mentioned something about the guard being in
the way.

You can't really do a plunge cut with a tile cutter - either use a
small grinder or a drill.