Aha - I thought this photo was familiar! It is of the Essex Yeomanry's detachment at the 1911 Coronation. It originally appeared in The Essex Yeomanry by J W Burrows (in his Essex Units in the War series) and is reprinted in The Yeomanry Force at the 1911 Coronation by R J Smith and R G Harris (Picton Publishing, 1988).
Mea culpa for describing the man at the centre, sporting the QSA & 5 clasps and KSA & 2 clasps, as an officer. He is 2742 RSM Walter Robert HADLER, 8th Hussars who served on the permanent staff of the Essex Imperial Yeomanry from December 1905, being promoted A/RSM in March 1911 . Hidden by his sword hilt is his Long Service and Good Conduct Medal that he was awarded in 1908. He was discharged in October 1914 to a commission as QM with the Essex Yeomanry and was later promoted to Captain.
(An aside: his son, born 1895, same name joined A Squadron the day after his 16th birthday and a few days after his father became A/RSM. Promoted Cpl Orderly Room Clerk in May 1912 (aged 17!), he joined the 17th Lancers in November 1913.)
So we can date the picture to 22 June 1911 or perhaps the day before.
Ian
