Well found again, Shaun. So that looks like the regular army, and not a Reserve. Even if he was moved to the Reserve later. Looking on Wikipedia, https://en.wikipedia.org/wiki/West_Yorkshire_Regiment, it looks as though the 7th and 8th Battalions were the Leeds Rifles and some were transferred to Territorial Reserve in 1916, so that would fit with later records. What do the numbers before the names mean? He has "8". I'm trying to find out if he actually went overseas.
Why is this going overseas important? I have been at pains to let you know that older men were essential to back up/release younger ones for fighting overseas. He was an older man at the time of WW1
Others have found that his rank was not doffed by him, out of the blue as a sort of status giving cap for the golf club but has been properly given. His work in Nigeria was in fact as District Commissioner and that was a fairly weighty and important role in the UK Colonial Service.
If he was called on to serve, whether this was in England or not, as part of the armed forces he deserves to be on the memorial and to have his service carefully explained.
Serving officers/men, I know for a fact in WW2 in NZ, did not exhibit the slightly sneering attitude towards their fellow soldiers who were doing work at home or who who did admin work while overseas. They realised that all were essential to the war effort and all should have their service recognised.
And yes school cadets/territorial force membership did count. Both gave a person a familarity with marksmanship and forces life and discipline. It was easier to slot these soldiers in than raw recruits. This was very important especially in the early stages of both wars.
My Uncle held gold medals for marksmanship in the territorial/cadet force he belonged to at boarding school here in NZ When he ran away at age 15 to join the AIF he was placed appropriately because of this. He was killed in France while acting as a sniper, well forward, when he was 18 years old. He was wounded a couple of times and I have the shrapnel that was removed....he saved it! Along with his medal swaps.
Various of his brothers were able to slot across, some with commissions, some without into NZ regiments early in WW2 because of their TF training that had followed on from being in cadets at school. TF training meant going away on camps etc a couple of times a year and was a commitment as some employers did not pay or did not pay the full wage, for this time away. (They do now)
Please be careful to be bland and factual in the descriptions and not put a gloss/denigration, that would not have been exhibited by fellow soldiers to those who served but who were too old or who were more valuable to the Armed forces held back because of other skills eg admin or being a NZ based gunnery instructor as happened with one of my Uncles in the early part of WW2.