There was some dispute about what colour his skin was. So I dug about and found his coat of arms, his will and a strange letter written in 1549 by Marion, Lady Hume, which refers to a 'Mour'...
My article, 'Sir Pedro Negro: what colour was his skin?' originally published in Notes & Queries in 2008, has now been posted on www.blackpresence.co.uk , a great site which aims to bring together information about Black British History and make it freely available online.