Thanks guys. It's in one of my books that BSA added it on the later frames, I can't find a picture of it with an actual sidecar fitting fitted in that place anywhere. Here's a photo of mine taken yesterday in preparation to a visit to Watsonion next week - so maybe they can throw some light on it. Also I'll try to find the reference to it I saw in one of my books. The hole is 22 mm long x 18 mm wide x 14 mm deep, so it's quite substantial. On my bike it's serving as a fixing for the battery carrier (it can also be seen in the 60 - 62 parts list). I've not seen it in photos of earlier frames.
I had a Canterbury double adult fitted to a previous G/Flash of similar age to my current one. That was way back in the late 60s through to mid 70s. An old school pal, who worked in the Motorcycle department of 'Kings of Oxford' (anyone remember them?) got it for me and helped me to fit it and set it up. I remember it was fairly easy, so it must have come with all correct A10 fittings. A year later I took it off (in the road outside a dealers) after they bought it from me for £10.00. I remember how and where the fittings go - except that one
.
Yes Roy, utilizing the tool box mounting hole (
and your A7 looks perfection).
(Edit); Roy, I'm looking at a GP Manx, been speaking with Ben, he said they'll make any necessary end fittings to fit the A10.