Just thought I should mention there is a William Leslie Burton who according to the death registration was born on 30 Dec 1908. The reference for the death registration is:-
William Leslie Burton
Aug 1990
aged 81 years
Liverpool 36 860
So if the dob is correct, his birth would have been registered in the 1st qtr of 1909.
Therefore, maybe the death in Gloucester wasn't your William after all.
Luzzu