Peter Howarth co-wrote the West End musical, "Robin, Prince of Sherwood", with 10cc guitarist Rick Fenn, which was commissioned and produced by Bill Kenwright. He also wrote songs with Fenn under the name 'Circle of 4'. They published a CD album called "and still I fly..." featuring 12 original songs. He sang backing vocals on the AOR album by Giant: "Last of the Runaways", released in 1989. The single "I'll see you in my dreams" reached 20 on the US Hot 100. In 2012, Howarth recorded "Last Goodbye" with Michael J. Mullins, with whom he had worked backing Cliff Richard.