Grumpy,
Followed your instructions and it worked perfectly. I ended up using a ring spanner (only 12 pt) and a socket on top and it worked perfecty. It took a little fiddling to get the clearances right however they are pretty close to spot on now. The pull start is much smoother than before the valves where adjusted.

The mower starts first pull and runs very smoothly. I gave it a good run last night (no smoke whatsoever) so its ready for a new home. Well most likely a small townhouse to ensure the small thing isnt too overworked. I have included a final photo below, note the very small catcher. I was pretty lucky to find it undamaged.
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