Interesting one...

There is Eliza BURTON in the 1881 census who was a nurse.

Eliza BURTON Head W Female 63 East Ilsley, Berkshire, England Monthly Nurse (S M S)
Albertina BURTON Daur U Female 18 Speenhamland, Berkshire, England Dressmaker

she was a widow at this time, so could have married Edward after this date. (Very unlikely given her age but not impossible) It would mean she would hev been abt. 82 in 1909. She was know to be seriously ill in 1910 and one can only presume that this could have been from old age.

This may all be the ramablings of a mad man but worth a thought.

Where is this letter now? Since he was married twice perhaps compairing his writting/signature from his marriage certificate(s) could be done.

Anyway a nice and fairly comforting story by all accounts. Have you tried checking the 1901 census to find potential locations at the time? I tried a vessel search but no SS Twynwald or SS Ellan Vannin came up.