I've just spotted the alias used by his wife (7 letters in another row) and together they total 16 letters. Is it just the wording in the preamble that is confusing me?
Glad you got there in the end Gitto. The puzzle was very tricky but definitely worth it in the end I thought. Getting the message was a serious breakthrough.
One letter base at the very end, preceded by three letter word for examine, check, surrounded by an extremely obscure old two letter word for that. You’ll think that can’t be a word, but it’s in Chambers. Answer is a name.