The 1984 Dawes catalogue was still listing the Galaxy as 5 speed. But from the late '70s a lot of people were replacing standard 5 speed with the Suntour Ultra 6 that could fit in the same space.

My Dawes is a replacement frame, sent by Dawes after the original developed a fault. That was sometime round about '84. The new frame has plastic cable guide under the bottom bracket, and is spaced 126mm at the back so would take a standard 6 speed. The original 1980 (or earlier) frame had cable stops to take housing under the BB.