Fitting kitchen worktops

[Stagcombo]

I've just fitted some worktops into a friends kitchen, using mason mitres.
These were replacement tops, with tiles already in place on the walls. I had some trouble fitting them in as the wall tiles made it difficult to scribe the mitres accurately.
Any techniques I could use, apart from taking the tiles off first?

 

[Scrit]

I sometimes rebate the back edge of the worktop to give me some clearance. This becomes essential when replacing 30mm tops with 28/40mm ones

Scrit

 

[Stagcombo]

Thanks, Scrit.