I am jealous. I only have the BSA Boys rifle....the Inglis has eluded me.
Your adapter may be someones manufacture to mount on either a M2 or a M3 Browning tripod.
You are looking for a mk2 bipod, which is hard to find. BRP in the US has the mk1 bipods which were modified to mount on the vickers. Perhaps their poor condition ones would fit the bill if it is the clamp that is damaged.
http://www.brpguns.com/vickers-machi...xiliary-mount/
If you really have your heart set on the mk2 bipod, Aleghany Arsenal has the right leg only.
http://mg34.com/product/boys-anti-tank-right-bipod-leg/
Numrich has the bipod mount listed for a mk2:
https://www.gunpartscorp.com/Products/349490.htm