An old thread I know, but this might help someone doing a similar search.
I have a pretty much identical Dawes Echelon to this, bought from new (in the UK) in 1977 for £75 when I was 16 years old. The only difference I can see is that mine has white gear lever covers instead of black. Dawes were not that common, and I chose this particular bike over contemporary models like the Carlton Corsa and Falcon Black Diamond because of the full alloy spec. The first thing I did, however, was get the plastic disc on the rear wheel removed (not cool!) and swapped out the pedals for some quills with toeclips (reflectors on pedals would have made me a laughing stock at the local cycling club!). The components were as follows:
Pacific Blue Frame – Reynolds 531 plain gauge. Steel forks. Frame number AC251, Davis 60, Components 62
Dawes engraved alloy handlebars, GB handlebar stem
SR Apex Chainset 52/40 rings
Weinman 750 Vainqueur 999 Rear brake, Weinman 610 Vainqueur 999 Front brake
Suntour V luxe No 4532 rear derailleur (later replaced replaced with Suntour Vx after the original got mangled)
Suntour Compe V front derailleur
Petissiez LF/QR alloy hubs and Birmalux 27x1-1/4" alloy 36 hole rims
Freewheel Regina (I think - it was later replaced) 14-24 5 speed
It handled beautifully and rode many thousands of miles on it, using it for time trials, touring, club runs etc until the mid eighties. I still use it today as a winter bike.