Somebody asked me off list what I knew about the Holdsworth Professional model. My apologies but I lost your name and Email address. But this is all I can remember. In the late 70's through to the early 80's there were three Professional models. Super Professional SL, Super Professional and Nuovo Professional. Differences as follows. 1. Super Pro SL Reynolds 531 Superlight Butted tubing. 74 degree parallel. Campag 1010B short ends. Prugnat long-point cut out lugs. Micro cast crown. Wrapover seat stays. Chrome drop-outs. Allen key fittings for Campag brakes. Finish Team Orange or choice.
2. Super Pro Reynolds built with 531 butted tubing. Same dimensions as Super Pro SL. Lugs are not cut out. Finished in Team Orange or choice.
3. Nuovo Professional Reynolds 531 butted tubing. Same dimensions as Super Pro SL. Vagner fork crown. Gargatte super bracket shell. Semi-wrapover seat stays and reinforced brake bridge. Finish Team Orange or choice.
Hope this can help in identifying your model.
Best wishes and be lucky. Michael Butler Huntingdon UK.