What unit is this mounted solider in?
 

I'd appreciate any help to identify the unit of the soldier in the photograph. The information below may help:

The soldier is my grandfather, Leslie Graham Collier. He lived in Harborne, Birmingham.
His medal card says he served in the Army Service Corps (Regimental number T/822) and the Corps of Hussars (Regimental number 305955).
He did not qualify for the 1914-15 Star so presumably joined in 1916 or later.
My father tells me that Leslie Graham Collier served in Mesopotamia. The only Hussars regiments which served in Mesopotamia were the 7th, 13th and 14th Hussars
The Absent Voters Registers of 1918 and 1919 show him as a Private in the 2nd Reserve Cavalry Regiment.
The 7th Hussars is the only regiment which served in Mesopotamia and which was reinforced by troops from the 2nd Reserve Cavalry Regiment
His regimental number 305955 was allocated to the Suffolk Yeomanry which did not serve in Mesopotamia but did service in Egypt.

Any help would be most appreciated

James

While he did not get the 1914/15 Star, thta only means that he was not in France or another operational area before 31 dec 1915. He may well have joined much earlier but never left England in timte to qualify for the medal.