I can't give you a positive ID, but I'll tell you this:
It has a variation of the style of fastback seatcluster known as "Brampton-Victor" or just Victor for short, coupled with the full-sloping crown one might jump to assuming a Raleigh Pro, but I'm not certain enough to jump, yet (you'd want 3 holes for the badge, not 2)
There were other British marques that did this style of seatcluster and had some kind of similar forkcrown: Holdsworth was one, Carlton perhaps another.
I'd guess it's certainly British and most likely 531 tubing and a 27.2 post.