Question: Where did the performers of The Number of the Beast form their band?

full_context: Document 1: The Number of the Beast (song): "The Number of the Beast" is a song by the English heavy metal band Iron Maiden. It is Iron Maiden's seventh single release, and the second single from their 1982 studio album of the same name. It was reissued in 2005 and also prior to that in 1990 in "The First Ten Years" box set on CD and 12" vinyl, in which it was combined with the previous single, "Run to the Hills".
Document 2: Run to the Hills: "Run to the Hills" is a song by the English heavy metal band Iron Maiden. It was released as their sixth single and the first from the band's third studio album, "The Number of the Beast" (1982). Credited solely to the band's bassist, Steve Harris, although significant contributions were made by lead vocalist Bruce Dickinson, it remains one of their most popular songs, with VH1 ranking it No. 27 on their list of the 40 Greatest Metal Songs and No. 14 on their list of the Greatest Hard Rock Songs.
Document 3: Iron Maiden (album): Iron Maiden Studio album by Iron Maiden Released 14 April 1980 Recorded January 1980 Studio Kingsway Studios, London, England Genre Heavy metal Length 37: 35 Label EMI Harvest / Capitol (North America) Producer Wil Malone Iron Maiden studio albums chronology Iron Maiden (1980) Killers (1981) Killers 1981 1998 remastered version cover Singles from Iron Maiden ``Running Free ''Released: 8 February 1980`` Sanctuary *'' Released: 23 May 1980 * Not an original album track, but added to later editions
Document 4: Best of the Beast: Best of the Beast was Iron Maiden's first "best of" album, released in 1996 in three formats: a 34 track (four disc) vinyl, a 27 track (two disc) CD, a 16 track (single disc) CD and MiniDisc. The vinyl edition is, to date, the band's longest record release, running for over three hours.
Document 5: The Clairvoyant (song): "The Clairvoyant" is a song by the English heavy metal band Iron Maiden. It is the band's nineteenth single and the third from their seventh studio album, "Seventh Son of a Seventh Son" (1988). The single, which was also released as a clear vinyl, debuted at number six in the British charts. It contains three live performances from Maiden's 1988 headlining performance at the Monsters of Rock festival in Donington Park.
Document 6: British Lion (album): British Lion is the debut solo album from Steve Harris, best known as the bassist and primary songwriter for the British heavy metal band Iron Maiden. The album was announced on 18 July 2012 and released on 24 September.
Document 7: Beast over Hammersmith: Beast over Hammersmith is a live album by the British heavy metal band Iron Maiden, released on 4 November 2002. Recorded 20 years previously, during The Beast On The Road tour at the Hammersmith Odeon, the footage was specially co-produced and mixed by Steve Harris and Doug Hall to be a part of the Eddie's Archive box set. Even though this album contains material from "The Number of the Beast", it was actually recorded two days prior to its release (although "Run to the Hills" had already been released as a single).
Document 8: Iron Maiden: Iron Maiden are an English heavy metal band formed in Leyton, East London, in 1975 by bassist and primary songwriter Steve Harris. The band's discography has grown to thirty-nine albums, including sixteen studio albums, twelve live albums, four EPs, and seven compilations.
Document 9: Sanctuary (Iron Maiden song): "Sanctuary" is the second single released by the British heavy metal band Iron Maiden. The single was released on 23 May 1980. Although originally issued as a non-album single, the song was added to the later US release of their debut studio record, "Iron Maiden" (1980). When the album was re-released in 1998, the song was added in all territories. In 1990, the 12" version was reissued on CD and 12" vinyl in "The First Ten Years" box set, in which it was combined with their first single, "Running Free".
Document 10: The Number of the Beast (song): ``The Number of the Beast ''is a song by the English heavy metal band Iron Maiden. It is Iron Maiden's seventh single release, and the second single from their 1982 studio album of the same name. It was reissued in 2005 and also prior to that in 1990 in The First Ten Years box set on CD and 12'' vinyl, in which it was combined the previous single,`` Run to the Hills ''.
Document 11: Run to the Hills: ``Run to the Hills ''is a song by the English heavy metal band Iron Maiden. It was released as their sixth single and the first from the band's third studio album, The Number of the Beast (1982). Credited solely to the band's bassist, Steve Harris, although significant contributions were made by lead vocalist Bruce Dickinson, it remains one of their most popular songs, with VH1 ranking it No. 27 on their list of the 40 Greatest Metal Songs and No. 14 on their list of the Greatest Hard Rock Songs.
Document 12: The Final Frontier: The Final Frontier is the fifteenth studio album by British heavy metal band Iron Maiden. It was released on 13 August 2010 in Germany, Austria and Finland, 17 August in North America, 18 August in Japan, and 16 August worldwide. At 76 minutes and 34 seconds, it is the band's second-longest studio album to date, a duration surpassed only by 2015's "The Book of Souls".
Document 13: Classic Albums: Iron Maiden – The Number of the Beast: Classic Albums: Iron Maiden -- The Number of the Beast is a documentary about the making of the album of the same name by the British heavy metal band Iron Maiden, released on 26 November 2001 as part of the Classic Albums documentary series. Directed by Tim Kirkby, it featured cuts from the title track, ``Children of the Damned '',`` Run to the Hills'', and ``The Prisoner, ''in addition to extended interviews and live footage of`` Hallowed Be Thy Name'', recorded during the band's performance at the Rock in Rio festival in 2001.
Document 14: List of Iron Maiden concert tours: Iron Maiden are a British heavy metal band, founded in 1975 by bassist Steve Harris in London, England. After several personnel changes in the 1970s, the band settled on a lineup of Harris, Paul Di'Anno (lead vocals), Dave Murray (lead and rhythm guitars), Dennis Stratton (backing vocals, lead and rhythm guitar) and Clive Burr (drums), before they set out on their first professional tour, the Metal for Muthas Tour which supported the compilation album of the same name. After taking on a supporting slot with Judas Priest on their British Steel Tour and setting out on their own headline tour in support of their debut album, "Iron Maiden", the band supported Kiss on the European leg of their Unmasked Tour, following which Stratton was dismissed because of musical differences. Guitarist Adrian Smith was hired, following which Iron Maiden set out on a short series of UK dates before recording their second studio album, "Killers".
Document 15: Running Free: "Running Free" is the debut single by Iron Maiden, released on 8 February 1980 on the 7" 45 rpm vinyl record format. It was written by Steve Harris and Paul Di'Anno. The song appears as the third track on the band's debut album "Iron Maiden" (and the fourth track on its 1998 re-release). In 1985, a live version of the song was released as the first single from "Live After Death" (the band's twelfth single). In 1990, the original single was reissued on CD and 12" vinyl as part of "The First Ten Years" box, in which it was combined with the band's next single, "Sanctuary". The 1985 live single was also released as part of this box set, combined with 1985's "Run to the Hills".
ground_truth: Leyton
sub_queries: The Number of the Beast >> performer Answer: Iron Maiden
Iron Maiden >> location of formation Answer: Leyton