After playing Matt of Sleaford (there's no such place as Slefern) he was a support actor in one heck of a lot of movies including many well-known Westerns, yet I'd never heard of him before... even though Westerns has always been a favourite subject of mine. Indeed this is one of my chief browsing books:
https://biblio.co.uk/book/bfi-compan...UaAkYEEALw_wcB
The book does feature bios for support actors who were frequently seen in Westerns as well as the stars, so I don't know why he's not in it.