This one is vexing. The 531 stickers look ca. 1982-3, but the frame looks a bit older. My best first guess was an early 80s Mistral, as they had ditched the lamp boss on the fork on all the other models by the end of the 70s, I think. But the Mistral came with 531st -- better than plain gauge 531, which is what this one is stickered as. And with bottle cage bosses and rack bosses. And I think the lugs are too fancy. Also, the standard "Holdsworth" font was different then. The top tube cable guides suggest it is not much earlier than early 80s; the rear gear cable routing and lamp boss rule out any later.
So I'm stuck on specific model, but I'll stick with 82-83. I've seen that font a couple of times before, but never known if it corresponds to a specific model.