Source: Glos Archives P78/1 IN 1/68 H, St Mary, Cheltenham, Burials, 27th April 1863 to 20th May 1863:-
There is NO entry for a burial of William POWELL during the above dates at St Mary, Cheltenham which is the main parish church in Cheltenham.
There is, also, up to a further 20 parish churches in Cheltenham which I couldn't possibly check.
Sorry I couldn't be of more help.
Victor