Hi - This is not quite the right thread - look under Eclipse - but mine is 060855. I am only guessing but that might mean 85/5 is May -85.
I had not heard about Holdsworth making the frames, people often quote Orbit as the frame-maker. By the 80s there was the Holdsworth shop in Putney - that made Roy Thame bikes, and there was Holdsworthy - you might ask Greg which one he used.
Is your bike complete - a photo would be good - they often seem to have come with Campag parts?
I would guess your numbering is a different 6-figure code say may be 1984, but that's just a guess.