Good afternoon,
Yes, 11th hussars, early to mid 1920s when still a mounted cavalry regt. They were one of the first two cavalry regt's to be mechanised in 1928, although it took several years to complete. The dress would have changed to that more suited to working in vehicles.
I'm not sure when they reverted to wearing their crimson trousers. But this has to be before then as well as I feel he would have worn them if possible for a photo.
John915