Background: Van der Graaf Generator are an English progressive rock band, formed in 1967 in Manchester by singer-songwriters Peter Hammill and Chris Judge Smith and the first act signed by Charisma Records. They did not experience much commercial success in the UK, but became popular in Italy during the 1970s. In 2005 the band reformed. The band formed at Manchester University, but settled in London where they signed with Charisma.
Context: Hammill's split with the group was amicable, and Banton, Jackson, and Evans, among others, all contributed to his solo work at various times. By 1975, the members of the band were ready to work with each other again, and they decided to reform the band. All the members were keen on carrying on with new music, with no nostalgia for their previous era, and did not want to play earlier stage favourites such as "Killer" (the opening track on H to He, Who Am the Only One) and "Theme One". "We didn't want to continue as if nothing had happened," said Hammill. The reformed band worked at a prolific pace, rehearsing, and touring France before recording three new albums in just 12 months, beginning with Godbluff (October 1975). Unlike the earlier work with John Anthony at Trident, the sessions were produced by the band themselves, and both the Melody Maker and Sounds thought they were a tighter and more cohesive unit than previously. The album in particular saw Hammill making significant use of the Hohner clavinet keyboard. Still Life followed on 15 April 1976. Banton considers this album one of his favourites by the group. In the summer of 1975, the band gigged in Italy without incident, but when they returned to tour there in November, the intense political situation the country was going through caught up with them. The opening concert in Padova was marked with clashes with communists delivering political speeches, and the audience started throwing missiles towards the stage. After a gig without incident in Genoa, the third day of the tour at the PalaSport in Rome, in front of 40,000 people, saw similar confrontations to the Padova gig. A fire broke out at the venue, but was brought under control. The next day, the band learned that most of their gear had been stolen from the tour van, including Hammill's blue Fender Stratocaster, christened "Meurglys". Despite threats from promoters that the band would continue the tour using hired equipment (which Jackson considered impossible given the electronic modifications he had made to his saxophones), they abandoned the tour. Miraculously, all of Jackson's saxophones had survived the theft. In December 1976, following World Record, Banton quit, quickly followed by Jackson in February 1977. Nic Potter returned to replace Banton, and in a typically eccentric move Jackson was replaced by a violinist, Graham Smith (formerly of Charisma folk-rock band String Driven Thing). This line-up produced the album The Quiet Zone/The Pleasure Dome (September 1977). The band also shortened its name to Van der Graaf. Charles Dickie then joined the band on cello, documented on the live double-album Vital, which saw a brief reunion with Jackson. By the time Vital was released, in July 1978, the band had already split, because of lack of record company support in the United States and financial difficulties. In 1982 a collection of out-takes and rehearsal recordings from the 1972-1975 hiatus was released (initially on cassette only), called Time Vaults. These are not studio-quality recordings.
Question: Who left

Answer:
Hammill's