Mr. Rusty - all noted thanks. Well I would cut them over the gap in my "workmate" vice. I did cut a few (thick) floor tiles this way once which was quite successful, so I was intending to try it with these wall tiles. your comment noted but I will have a try. Good point about toilets and basins - I am stripping these out anyway as they are in the wrong position for the new shower install!
Thanks KIAB - well I'l try my angle grinder method first and then if I ruin 10% of the tiles, I'll do what you suggest!