After the demise of the Pistols, Cook and guitarist Steve Jones, initially worked on the soundtrack to the Pistols film The Great Rock N'Roll Swindle. Becoming disillusioned with Malcolm McLaren's antics, the pair started a new band, the Greedy Bastards, linking up with several members of Thin Lizzy inclusing Phil Lynott. The band released only one single under the name The Greedies, entitled "A Merry Jingle". They performed several live shows but the band split within a year.
Cook and Jones later teamed up with a number of acts as freelance musicians, playing on Joan Jett's debut album. A proposed partnership with Jimmy Pursey and Dave Treganna of Sham 69 failed to materialise, so the pair formed their own band. The Professionals were formed with Andy Allen, who was replaced soon after by Paul Myers of Subway Sect together with Ray McVeigh. The group released two albums, but following a car crash in the U.S. the band split in 1982.
Cook then went on to appear with the group "The Chiefs of Relief" after a period out of the music industry, played with Edwyn Collins in the nineties and reunited with the Pistols in 1996 for the "Filthy Lucre" world tour.