SNAP! I've just taken delivery of a Galaxy frameset in the same blue (and with the same headtube badge)! I'd guess that yours is older than mine: no DTS bosses.
My frame number is AP1 185, so I don't think the last two digits are the year: if it was the other way around, I could believe it, ie yours was 85 and mine 91.
A few differences between the two: my TT cable guides are on top, my seatstays have flat caps and are engraved Dawes, rack mounts on seatstays and forks, my chainstay bridge is a tube, dropouts marked Dawes, SN on BB.
The frame (with steel HS races, no BB) weighs 2.18kg and the forks (with steel crown race) is 0.78kg; seatpost is 27.2mm: according to the Reynolds sticker it is made of 531st fork blade, stays& butted frame tubes.
Of course a model that has been in production so long is bound to have changed, but I would have expected to see rack mounts if it was a Galaxy.