The problem with the previous advice from Vincent is that the link provided for service records requires a death certificate (unless the death is in service) - and Pat says they are looking for the death certificate!
A tree on Ancestry suggests Thomas died in London 14 July 1953 at age 69 - if this is the corerct person he is unlikely to have died in service at age 69.
A death certificate can be purchased from the General Registry Office (www.gro.gov.uk) for around nine pounds, and there is a probate record that can be purchased for 10 pounds from www.gov.uk/wills-probate-inheritance, added together cheaper than the 30 pounds required for a service records search that might not even find anything.
