I'm sorry to hear that the legal historian AW Brian Simpson has died. There's plenty of detail in Christopher McCrudden's obituary in The Guardian.
Simpson's probably best known to folklorists (and most general readers) for Cannibalism and the Common Law, his classic account of the Mignonette tragedy and its ensuing legal case. (This established the precedent in English law that you could not kill someone to eat them, even in the most extreme of circumstances). I've written on the case here before.
It's an excellent book, rich with ballad and customary evidence, and it's invaluable for anyone trying to understand the clash between folk culture and the law. I used it extensively when I was working on Thackeray's poem about cannibalism at sea 'Little Billee' for an article in the Folk Music Journal, 9.5 (2010).
I don't know whether Brian Simpson ever saw this article, but he was certainly uppermost in my mind when I came to illustrate it. He had quoted a broadside ballad about the Mignonette, 'Fearful Sufferings at Sea: Lad Killed and Eaten', but wrote that he had never seen a copy of the ballad. It was serendipity that, while looking for ballad illustrations in the Vaughan Williams Memorial Library, I came across that very ballad in Ralph Vaughan Williams' own collection. It now adorns the cover of that issue of the journal. Its inclusion was always intended as, and remains, a small tribute to Brian Simpson's sterling work.