I had tried both angle grinder with carborundum disks (wore em out in
seconds) and chipping with a cold chisel (worked, but not on long thin
bits: They always cracked across) and so decided to hire an angle
grinder with diamond blade.

What a difference!

I hired it for a day, but did the job in just over an hour, cuttng all
te awkward bits around edges and steps in that time.

Like a knife through butter.

Cost me £17.92 and saved a whole load of broken slabs. I even cut down
some other broken ones to make new smaller ones.

Only problem is the cut is too clean. Still a couple of minutes of
distressing with teh cold chisle solved that :-)

Just passing this on to anyine who is doing similar.