Thanks Ady.
Family lore had it that Thomas was from a town called Hospital in Co. Limerick. I searched FindMyPast for his name born 1830-1850 and got 10 hits, one of whom was born in Limerick in 1840.
When I looked at the images it's definitely him, he spent 20 years in the 86th Reg of Foot, including a total of 10 years 5 months in Gibralter, Mauritius and the Cape of Good Hope, though the exact dates aren't shown. He was discharged in Belfast in 1880, shortly before he married.
I now want to know where he was stationed during the 1870's, which might help me find out if he was my grandfather's father or stepfather.
I've attached the last part of his Detailed Statement of Service which shows his last 10 years broken into 2 periods of 3 and 7 years. Does this indicate he was in 2 different places? There's also a period of about a week in 1872 which I think says "Insp by Comg Officer" which doesn't seem to count towards his accrued service, any ideas why? Also interested in what the lines in red ink mean.
Finally, would there be any diaries available for his regiment which would show where they were stationed during this time?