Nice :)
There's a thread on here about CB frame numbers that should nail it for you if you post up the number.
The Whitcomb with Haden lugs, over BB guides and the drilled chainset is probably 1977 (the last 2 digits of the number), the 531 sticker on it looks older though ?
Not quite sure what the seat tube decal is doing on the downtube. the 531 writing looks sloped and not horizontal which is maybe younger than the frame.
Nice though...........
Nice :) Classic chamfered seat stays of the Special...
Does Nick Kilgarrif website still work? there was a lot of Holdsworth info on there. the 7 in a diamond is the date of the cranks.
Smart Restoration :)
BITD there were several brands that were made for catalogues (Grattan, Empire Stores etc). In the absence of any leads may well be one of them.
I had a look at the download here
https://www.retrobike.co.uk/archive/1976-raleigh-catalogue.351/
Nothing matches exactly, however, there was a trend quite a few years back to grind off all brazings and convert to a "fixie" with a rattle can job.
Could be one of those...........