This envelope is addressed to Jimmy, rather than being from Jimmy (unlike the other 5). It is dated 29 June 1949, and the letter inside is dated June 28.
I have heard from Tennyson this morning about your sad loss. It must have been a cruel disappointment to both of you. Jessie and I can well understand how you feel and you have our deepest sympathy.
I know that words are not much help at a time like this but it may be some little consolation for you to know that you have friends who are thinking of you.
Yours very sincerely,
The choice of words 'cruel disappointment' make me think of a miscarriage or still birth, but whatever loss Jimmy and Marian suffered, I felt very sad when I discovered this letter. Percy sounds like a lovely friend.