its very similar to one I had late 80's. Mine was built in 531 comp, same BB shell and cast seat lug, fork crown and fork shape as yours. It was a mass produced one, not an Ilkeston one. Mine was a light blue fade around the head tube, fork crown and rear end and ruby read round the seat cluster and BB on a metallic white background. for such an ordinary frame, in many ways rode better than my colnago master. A mate who had a colnago super was peeved that he'd spent a bomb and my raleigh weighed a lot less. They also did one in 653 which was red and green on a white background.
given that it has a 27.2 seatpin its 531C or 653 and not 501 which i also had as a winter bike and used a smaller seatpin. At that time, you can tell if its mass produced or ilkeston, cos the mass produced ones had slightly larger than average welding blow-holes. The forks used to whistle different notes depending on speed of descent. Sound comical, but got quite annoying and eventually I put different forks on.
It will build as a good quality, lightweight racing bike.
Thought you'd be on this one.
26.8mm seatpost - very light. I have a similar era Raleigh 501 frame to comapare it to - so different