Great work Dave!
Impressive documentation and a great resource for all for narrowing the year and identifying model with help of catalogs on Kilgariff site. When I last counted a few days ago there were approx. 200 serial numbers listed on your excel spread sheet. Things are certainly becoming clearer as numbers are added. THE MORE NUMBERS THE BETTER!

I wasn't aware of early 70's 4 digit special numbers until recently after discussing a frame with Hilary Stone that he has for sale. (Often these frames appear to be factory models customized for smaller shop re-branding as example Harding)

Wileyone,
The Putney shop numbering system beginning with 2 digit year began on or shortly after '65 and continued until 1975 when Roy Thame was told by Holdsworthy headquarters to stop branding shop models as Holdsworths. Following '75 shop frames were branded Roy Thame.

Doug
(aka CBguy on Retrobike)