My memory of Hamish is of visiting him in his top-floor office at the School of Scottish Studies. The conversation was wide-ranging, sparking off in different directions, and Hamish mentioned that he'd seen a letter on the (whatever) topic earlier in the week. Then he turned to his desk and surveyed the 4 or 5 tottering piles of books and papers along the top of it; he reached for one pile, hand hovering over it, but changed his mind and instead delved unerringly into the middle of another one and unearthed an entirely inconspicuous piece of paper -- which turned out to be exactly the thing he had mentioned!
I'm now wishing I had the same gift....