Thanks for your concern but it seems I had the story slightly wrong (or my Mother did when she originally told it ).It seems that John Lamont did indeed go to Panama but at an earlier time ( when he was 16 )That was when the postcard was sent. He returned to Scotland when he was about 21. Everything else was correct and he did eventually disappear about the middle of the 1930's. My Mother is not sure of exact year.
Sorry to have mislead you but we still believe he headed for either the States or Canada.