The thing to do would be to try and discover the regiment (possibly the 66th Foot if he joined up in Berkshire - in which case he did very well to avoid service in Afghanistan and their eventual fate - Maiwand) and then check the muster rolls to see if he appears there.
Thank you -- Berkshire does seem to be where he would have been, so that is a very handy bit of info, and something to while away some time reading up on.
In this family there is a complex web of how people from apparently disparate geographic and socioeconomic backgrounds could have met -- we have the marriage in Berkshire in the mid-1870s of the rich heir boy from Wales (bankrupted in the 1880s, apparently as a result of fondness for the ponies) and the girl from Cornwall who was on the stage in London, Hill's sister, her economic situation just unfathomable, but whose estranged? father was in the same business as the boy's uncle: was it their family business connections, or was he a stage-door johnny?? On a birth certificate c1880, the husband is identified as late of 105th foot, and the Gazette shows him resigning his commission just before: possibly yet another way the couple could have met, i.e. through her brother the deserter if he and the rich boy were acquainted in India. And so that could be another place to look for Hill in the military. He appears to have followed the couple to where they settled after the rich boy left the military.
http://en.wikipedia.org/wiki/105th_Regiment_of_Foot_%28Madras_Light_Infantry%29(Looking for the rich boy here and there, it does not help at all that he had the exact same full name and was just about the same age as a very famous Admiral, which gave me 2 minutes of excitement when I first tried to figure out whom this previously unheard of sister had married ...)
I'm not sure about his 'contracted 5 years' … soldiers signed up for 12 years (after the 1870 Cardwell Reforms) - 6 in the Colours, 6 in the Reserve - with an option to extend to 21.
I know ... that 5 years does sound like a bit of a self-serving invention, doesn't it?

Thank you very, very much for your reply. If I ever find him in military records, I'll let you know here!
By the way -- a few years ago when I was first discovering all this, I happened to pick up the charity shop Penguin copy of Kipling's The Man Who Would Be King that had long been languishing on a bookshelf, and coincidentally, the Michael Caine / Sean Connery film version came on TV shortly after. I'm sure you know them, but for anyone who doesn't, a bit of English-in-Afghanistan historical fantasy (but don't read the plot!):
http://en.wikipedia.org/wiki/The_Man_Who_Would_Be_Kinghttp://en.wikipedia.org/wiki/The_Man_Who_Would_Be_King_%28film%29(Military problems run on both sides of my family: Hill's counterpart's son on my other side was discharged
with ignominy from the Dragoon Guards at the age of 16! He promptly re-enlisted under an altered name, gained a WWI battlefield commission, and went on to further ignominy in Ireland in the 20s. And another one on that side enlisted in the 9th regiment of foot on Christmas Eve 1814 at 16: very hungry, or very drunk?)