I know he was my great uncle on my fathers side.   He was from ballyhaunis, Co. Mayo.  He was working in London civil service , so joined London regiment (Prince of Wales Own, civil service rifles)  he was only 22 when he was killed in Somme . 

15th (County of London) Battalion, 
London Regiment (Prince of Wales's Own, Civil Service Rifles)
140th Brigade, 47th Division
Service number: 528715th (County of London) Battalion, London Regiment (Prince of Wales's Own, Civil Service Rifles)
140th Brigade, 47th Division
Service number: 5287

Brigid maguie