Eastpass - Presumably you have your relative's death certificate?
I don't think it's unusual for records to be missing, especially during the war. My gran was cremated in 1952, I didn't go as it was thought I was too young - I was 11 at the time - but obviously my dad and his siblings etc. were there so I know she was cremated but although the records for Manchester are on line, her cremation doesn't show up - so far. It could just be that the records haven't been put on line yet and in an area with lots of cemeteries that makes finding a burial/cremation difficult unless the authorities are helpful and will do a search for you.
My g.uncle died in 1964 in a mental hospital, he'd been there for almost 50 years but there is no burial record for him. I can only assume that he was buried in the communal grave at the mental hospital.
