There are some close-ups of older Dawes head badges here:
which suggests yours is newer than 1960.
There are some Dawes catalogues in the collection here:
which suggests they used that style of head badge by 1964. They were still using it in '69, when this Galaxy was made:
http://www.flickr.com/photos/adamslight ... otostream/
Those lugs are pretty distinctive, and I can't see any like them in any of the catalogues, but just going by the head badge, and features like the foil-backed decal panels and contrasting colours, a sixties date seems fair. Stock was probably slower to turn over in those days, and models didn't change every year in the way they do now, so it could well have been made in the mid to late sixties, and sold in 1970.
The '64 catalogue shows separate bolt-on cable guides along the top tube, while the '69 Galaxy has two brazed-on stops. Does yours have braze-ons?
Calmes dans le demi-jour
Que les branches hautes font,
Pénétrons bien notre amour
De ce silence profond.