Ah Pete. I was expecting some discolouration, just not a mm or 2 of soot.
I've had a read that rich running and crap fuel can cause this too.
Book states fuel as 95, not 97, so that's what she has, but I don't put known brands in, she has the 95 from the costcutter petrol station down the road. Never notice any difference when the occasional tank of BP goes in.
On another note, the new crank sensor is preventing hot start issues, so that's a good result.
Cheers for the reply either way matey. Hope you've sorted the belt.