Happy to be corrected, but I have to say this dose not fit nicely with any Holdsworth or RT numbers. I see the wrap over stay and the Club shaped cutouts in the lugs; RT did use these, but most of the examples I have seen had Holdsworth shop numbers, ths frame hasn't. RT used shop numbers up to 1980 and there are also some frame from the 70's with the holdsworth 4 digit numbers. RT then used 5 & 6 digit numbers in the 80/90's, they often started with letters but not a zero. Also they tended to be across the center of the BB.
I have to say I am not seeing this as a Holdsworth or RT.