There are a number of Able Seamans Johnson who died in 1841. Looking at a few I found one from Kent - could be more - my English geography is not very good.
Listening to the film it seems to be Harold Leslie Johnson - Son of John Thomas and Rebecca Jane Johnson, of Sittingbourne, Kent. Aged 21, died 29 May 1941. (From CWGC)
It seems they were found in Sittingbourne, Kent - they may quickly get claimed.
Trish
Edit: I wonder if the soldier was perhaps a brother-in-law?