John ,
Rethink as I think cap is Glengarry not brodrick
Period c. 1879, same tunic etc as worn in Zulu war Coat bright Red trousers Very Dark Blue [not suggesting shot in Africa!], glengarry and badge confirm this sort of date. The chevron is a Good Conduct badge: there is little uniformity as to which arm, or indeed both, around that time. As to regiment, impossible to say, except infantry and not Guards.