Bugger. Just gone and done a mistake that i keep doing when sculpting - focusing on one area so much that i forget to check how it looks in relation to the rest of it.
In this case i was so busy working out the arm and leg placement in the body that i didn't spot i was making him far too wide:
Not a lot i could do about it - except maybe if i widened out the "mouth" area so there'd be less meat there, it wouldn't be too pronounced.
So that's what i've done, hacking away at it with my junior hacksaw, revealing the layers of Bacofoil, card, tape and wire that i've used in the bodies construction: