John of London
John of London, mathematician, was described by Roger Bacon as one of two "perfect" mathematicians, together with Pierre [de Maricourt]. Bacon probably knew John in Paris in the 1260s.
No works are certainly attributed to him, but he may be the author of an influential table of stellar co-ordinates. He may also be the "Master John of London" who designed a form of astrolabe and was described by Roger of Lincoln as "astronomus famosus".