Galaxies are v.good bikes, but they weren't handbuilt - despite the claims made in marketing and on the bike(decals).
And never a good idea to date a bike on components...Dawes probably made too many to even begin to grasp the numbering system.
I guess if you can date it by paint finish - within a few years - that's the best you can expect.
Enjoy riding it.
Roadking.
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Founder of a V-CC section, member South Eastern Road Club. In the garage - 2005 Bianchi Reparto Corse (modern), 1986 Raleigh SBDU Pro Super, 1984 Raleigh LU Corsa, 1982 Geoffrey Butler (Roberts build), 1980 Roberts Road Classic, 1980 Allin Stan Butler Special, 1974 Ken Bird (Philbrook build), 1978 Geoffrey Butler, (Roberts build), 1976 Roberts tourer, 2 x early Roberts, 1966 Raleigh Superbe Roadster, 1964 Allin Stan Butler Special Belgique, 1951 Hobbs of Barbican S/C, 1950 Hobbs of Barbican S/C, 1947 Hetchins Super Special. MTBs - 1988 Specialized Stumpjumper, 1988 Muddy Fox Courier(Wife's).