I agree with James. He was in a British cavalry regiment. I also think the uniform is from the very end of WW1 into the 1920s, maybe even 1930s. So he could be the one born in 1905, and he was too young for WW1.
The service records of men discharged after 1920 are still with the MOD. They charge £30 and it can take 6-9 months. You could try the regimental museum first. They may not have any individual records. If they do they probably will not give you a copy. But they may be able to confirm he served with them. You should also ask for his army number. The MOD may insist on you providing his number. They will require a copy of his death certificate as well.
Ken
