Tin, indeed. I was searching Ancestry's WW1 Army records when I stumbled across records for my son in law's ancestors, not for WW1 but for middle 19th Century; they were in the WW1 record sets even though he had been discharged even before the turn of the century.
Fascinating reading. I think he had more time in the Army without pay than with pay. Another, from the same family branch, was recruited in September 1914 and discharged in December 1914 the charge sheet was interesting. Yet another had a slightly longer period in the Army before being discharged to the care of HMP Wandsworth.