The bits look in nice condition if not a bit grubby, but that looks minor and like theres shiny shiny underneath. If those are the original components its looks like its lead a very quiet life.
Chances are its a shop branded frame or possibly mail order similar to CRC or merlin, dressed up in a top groupset. Probably originally in the £1100 mark. It depends now who made the frame.
For this some details concerning the dropouts, welding, frame bosses and cable stops. Look everywhere if you can for frame numbers etc