Thanks guys...bookmark added.
I'd worked out that the point of moving on to the next step was when the area in question had been given a uniform finish. ie any crack would disappear. Then it would be a question of working down through the 'grit size'. I also came to the conclusion that one needed to keep the initial area as small as possible and that each subsequent finer applications would cover a slightly larger area than the preceding grit size thus ensuring that all the previous 'higher 'grit' size was polished over with the finer grit.
How to do it, though. Especially when we're talking only about a small scratch about 3" long. Answer...the Dremel ! Finally a use for those wee pads I'd had for the last ten years +
I'd already got these from China
They'd dried up a little but a poke with a paper clip freed them up. They range from 10 down to 0.5 which is perfect for my application. I tried the finest (0.5) on a piece of scrap to see if I could detect any difference in polish. If I could then the project was doomed at the start. Need not have worried. I couldn't discern where I'd applied the paste.
Dremel on lowest speed but TBH on another crack I simply used a paper towel and that worked just as well with the added bonus of not being splattered with paste as the Dremel whizzed round. So without further ado ..
BEFORE
and ten minutes later
AFTER
Result !
My only slight concern I have is that the paste does have a colour tint. There are some scratches in the other ensuite but that is my wife's pride and joy using Carrara marble and if I gave some of them a colour tinge ....you can guess the rest.
If opportunity doesn't knock, build a door.