Public Image Ltd (abbreviated as PiL) are an English post-punk band formed by singer John Lydon (a.k.a. Johnny Rotten), guitarist Keith Levene, bassist Jah Wobble, and drummer Jim Walker. The group's personnel has changed frequently over the years; Lydon has been the sole constant member. Following his departure from the Sex Pistols in January 1978, Lydon was eager to pursue a more experimental project and formed PiL. Later that year, the group released its debut First Issue (1978), featuring an abrasive, bass-heavy sound and drawing on elements of dub, noise, and progressive rock. Their second album Metal Box (1979) pushed their sound further into the avant-garde, and is often regarded as one of the most important albums of the post-punk era.

Following the Sex Pistols' break-up in 1978, photographer Dennis Morris suggested that Lydon travel to Jamaica with him and Virgin Records head Richard Branson, where Branson would be scouting for emerging reggae musicians. Branson also flew American band Devo to Jamaica, aiming to install Lydon as lead singer in the band. Devo declined the offer.  Upon returning to England, Lydon approached Jah Wobble (ne John Wardle) about forming a band together. The pair had been friends since the early 1970s when they attended the same school in Hackney (both belonged to a circle of friends Lydon informally dubbed "The Gang of Johns" - John Lydon, John Wardle, John Gray, and John Simon Ritchie, a.k.a. Sid Vicious). Lydon and Wobble had previously played music together during the final days of the Sex Pistols. Both had similarly broad musical tastes, and were avid fans of reggae and world music. Lydon assumed, much as he had with Sid Vicious, that Wobble would learn to play bass guitar as he went. Wobble would prove to be a natural talent. Lydon also approached guitarist Keith Levene, with whom he had toured in mid-1976, while Levene was a member of the Clash. Lydon and Levene had both considered themselves outsiders even within their own bands. Jim Walker, a Canadian student newly arrived in the UK, was recruited on drums, after answering an ad placed in Melody Maker.  PiL began rehearsing together in May 1978, although the band was still unnamed. In July 1978, Lydon officially named the band "Public Image" (the "Ltd" was not added until several months later), after the Muriel Spark novel The Public Image.  PiL debuted in October 1978 with "Public Image", a song written while Lydon was still a member of the Sex Pistols. The single was well received and reached number 9 on the UK charts, and it also performed well on import in the US.Answer this question using a quote from the following article:

When did the band form?
1976,