Apologies for dumb question but planning out refit of bathroom and wondering if possible to tile a sloping part between the wall and ceiling?  Will the adhesive be strong enough to help the tiles defy gravity?!  We are hoping to squeeze a shower in a small space but unless can tile the sloping part doubt it is going to work.

Yes you can stick tiles to angled walls. Ideally you don't want to use really think (read: heavy) tiles and a good adhesive. Like CWatters said, you need good backing because the last thing you need is a load of tiles on your head in the shower. You can also prop the tiles up with adjustable props until they set, don't do more than 1 row at a time and allow to set sufficiently before moving to the next row.

I personally would not tile an angled wall because too many things can go wrong. There are some very good products on the market that will waterproof your wall, without the need for tiling.

Thanks for the replies.  Reassuring to know can be done and that there are alternatives to tiles.  Will get on with planning bathroom in more detail.