Originally Posted by unworthy1

When Reynolds revised the line (and graphics on the decals) around '82 and afterward, the tubesets also got some revisions, 531 'Super Lightweight" (AKA Red Label 531) transitioned to "Professional".
Tho the OP's example has the post '82 style frame decal, the original "Red SL" came with green label triangle transfers for the forkblades and presume that Saracen either was being very honest about what blades they built the fork with, or could be they lost the red blade decals (or built this one with mixed vintage).
In any case I don't think it's any frame to sniff at, even if the stay ends were left domed. BTW I don't know who made that seat lug but yest it's interesting and deserves some close-ups. Appears to be IC, which the early-ish Cinelli BB shell is too (that's a SCM model shell, replaced by the CCM with chainstay sockets "rotated 90 degrees")
Congrats on the purchase!