Needed to update this Topic for additions, plus it may help others.
I obtained the Illustrated Parts List for this Chainsaw from the original owners who purchased it in March '72' in the UK.
The IPLs (attached here) are dated 9/71, so the Saw is a very early model example-
XXVModel25.pdf
With the IPLs, I have been able to reproduce the Felling Spike which was an optional extra for this model. For now, I made one from old 1. 3/8" (35-ish mm) mild steel box section-
Marked it out (scribed 'n' pen) rough first-
Next thing to do was to heat it up to cherry red for a few minutes to take the stresses out of it, as it is ERW formed box.
Cut it out and cleaned up, then added a few tweaks to shape it and fitted with some 1960s chrome 10 x 24 UNC Setscrews-
I'll give this Spike a Case Hardening session, as I've ran out of 3/32" Gauge Plate and have to order some more to make a pukka hardened example from this pattern.
Regards