Well seeing the collar badge (it is a bit blurred) it could fit the Inns of Court Regiment.
It is a bit strange history. It was a Middlesex Rifle Volunteer Corps from 1860 (but existed earlier).
It should have become the 27th (County of London) Battalion (TF),
The London Regiment in 1908, but ignored this and and became the
Inns of Court OTC (TF) instead. It was resurrected in the TA as such.
In 1932 it had Cavalry as well as Infantry (but It wasn't Yeomanry) as
The Inns of Court Regiment.
In 1940 it was transferred to the
Royal Armoured Corps.
See also:
The Inns of Court Regiment.
And my trial to compress this into a table:
Middlesex - London
Nice set of medals BTW. Good that they are kept as family treasure.