Re [CR] Colnago track frame

I have just turned up what I think is a fairly early Colnago track frameset. Can anybody suggest a time period for this frame? It is of distinctly better quality than I have seen on many Colnagos - but perhaps this is because it is a track frame which were always built in much smaller numbers than road frames. Pictures can be seen at:

http://images.andale.com/f2/118/129/2070911/1045520679928_Colnago_bb.jpg

http://images.andale.com/f2/118/129/2070911/1045520678935_Colnago_head.jpg

http://images.andale.com/f2/118/129/2070911/1045520679524_Colnago_frame_no.j pg

http://images.andale.com/f2/118/129/2070911/1045520677896_Colnago_seat_lug.j pg

http://images.andale.com/f2/118/129/2070911/1045520678467_Colnago_overall.jp g

Hilary Stone, Bristol, England