1980's Chas Bland in Reynolds Designer Select tubing. 100/127 spaced with short point lugs, 'shot in' rear stays. Fork has an internal aero crown so probably late 80's. Built in a 'crit' style with a higher BB for better cornering...and it works. Thinks it around 57 ctc seat tube but I'll confirm, I'm just a wee tad over 5'10 but it will suit someone a bit taller.
I did manage to break a rear dropout when I broke Campag axle? Chas repaired free of charge and was ridden a few years after without any issues.
Too nice a frame to scrap as it rides as any good 531 frame should.
Worth every penny of £100 to me.