I found this paper, interestingly enough, as a loose insert in the used book I had received from England. The name of the book is THE TURBULENT LONDON OF RICHARD II. The book is practically unreadable, but does preserve lots of names and minutiae from the period that are of no interest to almost anybody. But you never know! This paper was stuck in the back; it appears to be from a different source altogether. I found it most helpful (if you click on it and click again with the magnifying glass, you will get full size):
Geoffrey Tobin says:
I don’t see Mr Londonstone on that list.
A number of the early Mayors of London are identifiably Breton, for example Alan of the (de la) Zuche/Zouche family who were barons in Leicestershire.