Question: What song did Led Zeppelin record at Headley Grange in February of 1975?
Context: "Custard Pie" is the opening track on the English rock band Led Zeppelin's sixth album, "Physical Graffiti", released in 1975. Led Zeppelin songs have been the subject of cover versions on occasion; American band Dread Zeppelin have made a career out of covering and parodying Zeppelin tunes.  However, other serious and authentic-sounding tribute bands have also emerged, striving to keep the true essence of a Led Zeppelin live show experience alive such as the Brazilian "Led Brazil" and Swan Song - A Tribute to Led Zeppelin, In the Light, and the British band Fred Zeppelin, who are based in the Black Country homeland of Plant and Bonham and have been seen by Robert Plant several times.  Lez Zeppelin is also an all-female tribute act, performing the work of Led Zeppelin. "Misty Mountain Hop" is a song from English rock band Led Zeppelin's untitled fourth album, released in 1971.  In the United States and Australia it was the B-side of the "Black Dog" single, but still received considerable FM radio airplay.  It was recorded at Headley Grange, a mansion with a recording studio in Hampshire, England, where the band sometimes lived. Headley Grange is a former poorhouse in Headley, Hampshire, England, UK.  It is best known for its use as a recording and rehearsal venue in the 1960s and 1970s, by acts including Led Zeppelin, Bad Company, Fleetwood Mac, Genesis, Peter Frampton, the Pretty Things, Ian Dury and Clover. Physical Graffiti is the sixth studio album by the English rock band Led Zeppelin, released as a double album on 24 February 1975 by their newly founded imprint label Swan Song Records.  The band wrote and recorded eight new songs for the album at Headley Grange, which stretched the total time of the record beyond the typical length of a single LP, so the band decided to make "Physical Graffiti" a double album by including unreleased tracks from earlier recording sessions: one outtake from "Led Zeppelin III," three from "Led Zeppelin IV," and three from "Houses of the Holy", including the unused title track from the latter album. The untitled fourth studio album by English rock band Led Zeppelin, commonly known as Led Zeppelin IV, was released on 8 November 1971 by Atlantic Records.  Produced by guitarist Jimmy Page, it was recorded between November 1970 and January 1971 at several locations, most prominently the Victorian house Headley Grange. "White Summer" is a guitar instrumental by English rock guitarist Jimmy Page, which incorporates Indian and Arabic musical influences.  It was initially recorded and performed with the Yardbirds and later included in many Led Zeppelin concerts.  According to biographer Keith Shadwick, it is based on an old Irish folk song, "specifically derived from 'She Moved Through the Fair' in the 1963 version by [Davy] Graham, which he in turn credited to Padraic Colum".  The later Led Zeppelin song "Over the Hills and Far Away" was "spun off" from "White Summer" as well as an unreleased 20-minute instrumental recorded in early 1974 at Headley Grange. The discography of the English rock band Led Zeppelin consists of nine studio albums, four live albums, nine compilation albums, 16 singles and eight music downloads. Formed in London in 1968, the group consisted of guitarist Jimmy Page, singer Robert Plant, bass player John Paul Jones, and drummer John Bonham.  The band pioneered the concept of album-oriented rock and often refused to release popular songs as singles.  Nevertheless, four of their ten songs that reached the Hot 100 had no mention of the title in the lyrics: "Immigrant Song", "Black Dog", "Over the Hills and Far Away", "D'yer Mak'er".  Their debut album, "Led Zeppelin" (1969), released by Atlantic Records, charted at number six on the UK Albums Chart and at number ten on the United States "Billboard" 200.  It received several sales certifications, including an 8 times multi-platinum from the Recording Industry Association of America (RIAA) and Diamond from the Music Canada.  Led Zeppelin's second studio album, "Led Zeppelin II", recorded when the band were on tour, was released a few months after the first.  It reached number one in several countries, including the UK and the US, where it was certified 12 times multi-platinum.  The album produced Led Zeppelin's most successful single, "Whole Lotta Love", which peaked at several music charts in the top 10. " Led Zeppelin III" (1970) was a softer, more folk-based effort compared to the hard rock of the band's previous releases.  It also peaked at number one in the UK and in the US. Bad Company is the debut studio album by the English hard rock supergroup Bad Company.  The album was recorded at Headley Grange with Ronnie Lane's Mobile Studio in November 1973, and it was the first album released on Led Zeppelin's Swan Song Records label. The Zeppelin Record is the fifth studio album by Dogbowl, released in September 1998 by Lithium Records.  Released five years after 1993's "Project Success", "The Zeppelin Record" marked the first time Dogbowl had not issued an album through Shimmy Disc and had gone without the collaborative aid of his brother Christopher Tunney and producer Kramer.  Instead, he opted to produce the album himself in Paris, where he had been living with his wife and children.
Answer: Custard Pie