Jethro Tull are a British rock group formed in Blackpool, Lancashire, England, UK during 1967. At first playing blues rock, the band then began including elements of hard and folk rock to create a progressive rock sound. Tull is led by vocalist/flautist/guitarist Ian Anderson, having had a revolving door of lineups over the years, significant members having been guitarists Mick Abrahams and Martin Barre, keyboardist John Evan, drummers Clive Bunker, Barriemore Barlow, and Doane Perry, along with bassists Glenn Cornick, Jeffrey Hammond, John Glascock, and Dave Pegg. The group first broke through in 1969, with the folk-tinged blues album Stand Up, which topped the UK charts then toured regularly there and in the US. Their musical style moved in the direction of progressive rock with the L.Ps Aqualung (1971), Thick as a Brick (1972) and A Passion Play (1973), before shifting again towards hard rock mixed with folk rock, with Songs from the Wood (1977) and Heavy Horses (1978). Jethro Tull have sold an estimated 60 million albums worldwide, with 11 gold and 5 platinum L.Ps. They've been described by Rolling Stone magazine as "one of the most commercially successful and eccentric progressive rock bands".