Hi Tim,
I've been "collecting" Holdsworth serial numbers for 3 or 4 years and have about 50 plus another 20 which I haven't added to the list. From What I see from my listings is that Holdsworth started with 4 digit numbers dating back into the 1940s and in early 1950s went to a 5 digit number which became a 6 digit number in the 1970s which lasted into the 1980s. Also the headbadges changed from brass to aluminum to brass to decals. Your 7229 could place it in the late 1940s. Does it have a brass headbadge? My data gets much better with the 5 digit numbers. Maybe one of these days I'll update my record and have a better picture.
Cheers,
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