Wow, looks like the old tiles were fixed with contact adhesive.
Gray grout on floor.
Bossed plaster,remove.
May have to provide key and primer on painted sections.
Here's the final result, I learnt lots by my mistakes, biggest f up was my drilling the tap holes in the wrong place-aagghhh- went to the pub after this and got myself quite irate over such a silly mistake,- made up some ss washers and had them chrome plated, best i could do really.
Not exactly my choice of tile but it keeps the supervisor happy.
Having never tiled or fitted a bathroom before im happy with the end result, thankfully, so is the boss.