Hi
The only solid info I have is that he fathered two children in 1905 and 1906 in Warwickshire. The first was born in Erdington, the second in Edgbaston.
The mother was from Walsall and lived in Kenilworth in 1901 and Leamington thereafter. They never married and both children were given up for adoption. I have posted other threads, but have never researched the military route.
His occupation in 1905 was stated as accountant and in 1906 as bank clerk. I thought the middle name 'Day', being quite unusual would help but this has not proved to be the case. I cannot find any exact match.
My main suspect was born in the Birmingham area, but I would stress that this is based on proximity, occupation and age - nothing concrete!
Hence starting down this route. I would think that the youngest he could be at the outbreak of WW1 would be 24 but more likely around later twenties.
Sorry I have no more to go on.
Tracy