Complex sentence: Warman had had a long standing friendship with Ringo Starr which went back to 1977 at Ring O'Records and when Starr started working on his first studio album in nine years Warman was asked to contribute towards the album in a song writing capacity.
Split into simpler sentences: Warman had had a long standing friendship with Ringo Starr since 1977 at Ring O'Records. When Starr began work on his first studio album in nine years Warman was asked to contribute in a song writing capacity.