Mike.
Hopefully this may help you:
South Middlesex Rifle Volunteers were the 2nd Middlesex Rifle Volunteers, formed 14th October 1859.
The cap badge you show can be found with both QVC and KC. I have examples in white metal, blackened brass and brass.
The collar badge is based on a founder member of the unit, Viscount Ranelagh’s crest and described as ‘a dexter arm embowed in armour and grasping a dart’ and were worn as facing pairs.
1st April 1908 they became the 10th Battalion Middlesex Regiment.
If you wish, have a look through my Middlesex RV album, (which I must admit needs updating) on the link below and you will find the examples therein.
https://www.britishbadgeforum.com/fo...p?albumid=1832
Regards.
Brian