Complex sentence: New metropolitan counties were created to cover the six largest urban areas in England outside Greater London, and these were subdivided into metropolitan districts, all of which inherited or have been granted Royal Charters to give them borough or city status.
Split into simpler sentences: New metropolitan counties were created to cover the six largest urban areas in England outside of Greater London, and these were subdivided into metropolitan boroughs. The new authorities were actually defined in law as metropolitan districts, however, all of them inherited, or have been granted Royal Charters and given borough or city status.