If he was born 1837, then we're probably looking for his military service sometime between 1855 and 1877 (age 16-40). He's not listed on the 51st's medal roll for the Afghan War 1878-80, which would lend weight to this idea.
Apart from home service in England & Ireland, the 51st spent much of the period in India. (India 1857-67, home 1867-72 then back to India 1872-87). As far as medals go, a lookup on the India General Service Medal roll may find reference to him. 51st were in the Umbeyla campaign 1863 and also qualified for the NW Frontier clasp.
For his papers, you will have to either visit Kew or bide your time till they get released online.