At this point I'm thinking that when all else fails, brute force and ignorance is the way forward so off I went to B&Q for a wire brush attachment for a drill.
The result, after half an hour..
Managed to find my engine number, wondered where it was!
As I left it before going for a shower and collapsing on the sofa..
Still plenty to get off in places I can't quite get to. Might have to resort to purchasing a Dremel.
Also, what is the best way of removing carbon deposits from a piston?
Soak in carb cleaner??
Mine are horrendous, this is Piston no. 1 and is actually the cleanest of the 4..
Any ideas?