I am planning the replacement of bathroom suite. Looking at the waste
pipe coming from the back of the WC it appears it was installed with
some "make-do" cutting of the pipe to accommodate an unusual angle
into the waste pipe running to the stack which is on the other side of
the house.

What way is recommended for cutting such a big pipe? Hacksaw, angle
grinder?

Cutting before fitting should make it a do-able job for me but until I
take up the floorboards I don't know whether any cutting will be
necessary of the pipe while in place. What suggestions does anyone
have to help if that is needed?

km