Ranging pole support manufactured by Holbro. This item is listed in Holbro’s 1969 catalogue, it says:
This support is robust and the centre castings are of aluminium. The legs are made from rust-proofed steel, and one of them is adjustable for use on uneven ground. Approximate weight 2⅜ lbs. (1.18 kgs).
Holbro’s 1969 catalogue has the catalogue number RP 751.
See 1996/043 for a matching ranging pole.