Dear Sunbeam
I researched this issue extensively whilst helping a friend produce a replica A10/A7 battery carrier. BSA used three carriers for swinging arm pre-unit twins:
Part 42-4515 - Early battery base plate/carrier for A group 1954-on which requires three battery straps and two trunions. These carriers may also fit BSA B31/B33 and Gold Star swinging arm models depending on year etc.
Part 42-4644 - Battery base plate/carrier, this part has a front plate welded to 42-4515 to which the wire clip you refer to is clipped. This plate has a bolt hole with a 2 BA nut welded to it* as support for the special air filter fitted to the A7 [after frame GA7-8855] and A10 [after frame GA7-8437]**.
Part 42-4651A - Battery base plate/carrier for A7SS [after frame GA7-8929], A10SR [after frame GA7-8618]**. This part also has a front plate welded to 42-4515. There is a hole in front plate but with no 2 BA nut. This nut wasn’t needed to support the air filter as this carrier was for A7SS and A10SR models which would usually be fitted with the alternative more sporty (i.e. less restrictive) ‘pillbox’ air filter.
* see
https://www.a7a10.net/forum/index.php?topic=9055.0** see BSA A7/A10 parts book 00-5086.
I think the RGS would ‘normally’ use part 42-4651A. However, these models were assembled by BSA at the end of the A10 production run in 1962-3 with whatever was to hand, to a buyer’s individual specification, and some may have been built from spares by George Dow himself. And of course there are a very large number of ‘replicas’ out there now which may or may not have correct parts on them.
I attach an enlarged picture of the illustration in the 1963 UK catalogue which shows a battery carrier front with a plate welded to it.
The carriers with a front plate welded to it are available in stainless steel and are dimensionally correct as they used an original BSA carrier of mine as a pattern. See:
https://classicbikepartsuk.uk/product/bsa-a10-rgs-b31-battery-carrier-tray-air-filter-bracket/I have no link with the company other than as a very satisfied customer.
Regards
Martin