Jethro Tull are a British rock group. Their music is characterised by the vocals, acoustic guitar, and flute playing of Ian Anderson, who has led the band since its founding, and the guitar work of Martin Barre, who has been with the band since 1969, after he replaced original guitarist Mick Abrahams.Formed in Luton, Bedfordshire, in December 1967, initially playing experimental blues rock, they later incorporated elements of classical music, folk music, jazz, hard rock and art rock into their music.Jethro Tull have sold more than 60 million albums worldwide. They have been described by Rolling Stone as "one of the most commercially successful and eccentric progressive rock bands".1962–68: originsIan Anderson started his first band, the Blades, in Blackpool, England in 1962. The group featured Anderson on vocals and harmonica, Jeffrey Hammond on bass, John Evans on drums, and a guitarist named either Hipgrave or Michael Stephans. Drummer Barrie Barlow became a member in 1963 after Evans had switched from drums to piano. By 1964 the band had developed into a seven-piece Blue-eyed soul band called the John Evan Band (later the John Evan Smash). By this point Evans had shortened his surname to "Evan" at the insistence of Hammond, who thought it sounded better and more unusual.In 1967, the band moved to the London area, basing themselves in nearby Luton; they also travelled to Liverpool. However, money remained short and within days of the move most of the band quit and headed back north, leaving Anderson and bassist Glenn Cornick (who had replaced Hammond) to join forces with blues guitarist Mick Abrahams and his friend, drummer Clive Bunker, both from the Luton-based band McGregor's Engine. At first, the new band had trouble getting repeat bookings and they took to changing their name frequently to continue playing the London club circuit. Band names were often supplied by their booking agents' staff, one of whom, a history enthusiast, eventually christened them "Jethro Tull" after the 18th-century agriculturist. The name stuck because they happened to be using it the first time a club manager liked their show enough to invite them to return. They were signed to the blossoming Ellis-Wright agency, and became the third band managed by the soon-to-be Chrysalis empire. It was around this time that Anderson purchased a flute after becoming frustrated with his inability to play guitar like Eric Clapton:"I didn't want to be just another third-rate guitar player who sounded like a bunch of other third-rate guitar players. I wanted to do something that was a bit more idiosyncratic, hence the switch to another instrument. When Jethro Tull began, I think I'd been playing the flute for about two weeks. It was a quick learning curve...literally every night I walked onstage was a flute lesson."Released in 1968, their first single, "Sunshine Day", written by Abrahams and produced by Derek Lawrence, was commercially unsuccessful. On the original UK MGM 45 rpm record label, the group's name was misspelled "Jethro Toe", making it a collector's item. Anderson questions the misnomer as a way to avoid paying royalties. The more common version, with the name spelled correctly, is actually a counterfeit made in New York.They released their first album This Was in 1968. In addition to music written by Anderson and Abrahams the album included the traditional "Cat's Squirrel", which highlighted Abrahams' blues-rock style. The Rahsaan Roland Kirk –penned jazz piece "Serenade to a Cuckoo" gave Anderson a showcase for his growing talents on the flute, an instrument which he started learning to play only half a year before the release of the album. The overall sound of the group at this time was described in the Record Mirror by Anderson in 1968 as "a sort of progressive blues with a bit of jazz."Following this album, Abrahams left after a falling out with Anderson and formed his own band, Blodwyn Pig. There were a number of reasons given for Abrahams' departure: he was a blues purist, while Anderson wanted to branch out into other forms of music; Abrahams was unwilling to travel internationally or play more than three nights a week; or there was simply no way a band could exist with two strong-minded heads (Anderson and Abrahams) pulling it in different directions. Abrahams himself described his reasons more succinctly: "I was fed up with all the nonsense, and I wanted to form a band like Blodwyn Pig."Guitarist Tony Iommi, from the group Earth (later renamed Black Sabbath), took on guitar duties for a short time after the departure of Abrahams, appearing in The Rolling Stones Rock and Roll Circus, in which the group mimed "A Song for Jeffrey" in December 1968. Iommi returned to Earth thereafter. David O'List of The Nice also deputised on guitar with Jethro Tull for a few shows and was briefly considered as a permanent replacement for Abrahams, although these plans never materialised.Other musiciansFollowing the departure of Mick Abrahams in 1968, Black Sabbath guitarist Tony Iommi briefly played guitar for Jethro Tull. The only recording of him with the band is on The Rolling Stones Rock and Roll Circus (1968), although his guitar is not heard as all of the music (except Ian Anderson's vocals and flute) was dubbed in afterwards. It was a one-off performance, and Iommi returned to Black Sabbath (then called Earth) in January 1969.David O'List briefly played with Jethro Tull in 1968 after the expulsion of Abrahams.Genesis' Phil Collins was Jethro Tull's drummer for only one gig: the Prince's Trust Gala on 7 July 1982 at London's Dominion Theatre. During this time, Jethro Tull had the position of drummer to fill after the departure of drummer Mark Craney. Collins played on three songs, and two of them ("Jack in the Green" and "Pussy Willow") are on an official video release of the Prince's Trust Gala.Bassist Tony Williams filled in for part of a tour when John Glascock's health failed. He then returned to session playing.Bassist Matthew Pegg – Dave's son – is credited with playing bass on Catfish Rising (1991), when his bald father was "washing hair". He also filled in on several dates in the early 1990s. He is currently a session musician, and was also a permanent member of Procol Harum.Bassist Steve Bailey appeared on the Roots to Branches (1995) recording, due to Dave Pegg's scheduling conflicts and following departure from the band. He was never an official member of the band.Drummer James Duncan has frequently appeared with the band from 2006 forward, as well as on Anderson's solo tours. Surgery performed on Doan Perry required him to cease playing for some time, and while he has returned to the band, Duncan continues to play some shows. Duncan is Ian Anderson's son.Florian Opahle, a German guitarist who has played on Anderson's solo tours, as well as with Greg Lake, has recently filled in for Barre on occasion, most notably due to the latter's recuperation from surgery, and in 2009, his playing in "Excalibur: The Celtic Rock Opera".Mark Mondesir is a British drummer mostly noted for his jazz work. He drummed with Tull and Ian Anderson as a fill-in for James Duncan in 2009, who broke a shoulder whilst skiing.Guitarist Joe Bonamassa guested with Jethro Tull for the encore of their performance at High Voltage 2011.Scott Hammond, a British jazz drummer, replaced Mark Mondesir for Ian Anderson's 2011 concerts. Hammond continues to tour with Anderson in 2012, and he played on the new Anderson album, Thick as a Brick 2, which was released in April 2012. Hammond also filled in for Doane Perry during Jethro Tull's concerts in 2011.Since 2005, subsequently Lucia Micarelli, Ann Marie Calhoun and Anna Phoebe played violin regularly with the band.