Background: Madness are an English ska band from Camden Town, north London, who formed in 1976. One of the most prominent bands of the late 1970s and early 1980s 2 Tone ska revival, they continue to perform with six of the seven members of their classic line-up. Madness achieved most of their success in the early to mid-1980s. Both Madness and UB40 spent 214 weeks on the UK singles charts over the course of the decade, holding the record for most weeks spent by a group in the 1980s UK singles charts.
Context: The core of the band formed as The North London Invaders in 1976, and included Mike Barson (Monsieur Barso) on keyboards and vocals, Chris Foreman (Chrissy Boy) on guitar and Lee Thompson (Kix) on saxophone and vocals. They later recruited John Hasler on drums and Cathal Smyth (better known as Chas Smash) on bass guitar. Later in the year, they were joined by lead vocalist Dikron Tulane.  This six-piece line-up lasted until part way through 1977, when Graham McPherson (better known as Suggs) took over the lead vocals after seeing the band perform in a friend's garden. Dikron went on to be an actor under the name Dikran Tulaine. Smyth, who left after an argument with Barson, was replaced by Gavin Rodgers, Barson's girlfriend's brother. McPherson was kicked out of the band for too often choosing to watch Chelsea instead of rehearsing. Thompson left the band after Barson criticised his saxophone playing.  By 1978, the band had allowed McPherson to return, after filling in temporarily for Hasler (who had taken over vocals when McPherson was removed). Thompson returned after patching things up with Barson. Drummer Daniel Woodgate (Woody) and bass player Mark Bedford (Bedders) also joined the band, replacing Garry Dovey and Rodgers, respectively. After briefly changing their name to Morris and the Minors, the band renamed itself as Madness in 1979, paying homage to one of their favourite songs by ska/reggae artist Prince Buster. The band remained a sextet until late 1979, when Chas Smash rejoined and officially became the seventh member of Madness as a backing vocalist and dancer.  During 1979, the band began to attract a live following in London, being regulars at the Dublin Castle in Camden Town. The band's first commercial recording was the Lee Thompson composition "The Prince". The song, like the band's name, paid homage to their idol, Prince Buster. The song was released through 2 Tone Records, the label of The Specials founder Jerry Dammers. The song was a surprise hit, peaking in the UK music charts at number 16. A performance of "The Prince" on popular UK music show Top of the Pops helped Madness gain public recognition. Madness then toured with fellow 2 Tone bands The Specials and The Selecter, before recording their debut album.  That debut album, One Step Beyond... was released by Stiff Records. The album included a re-recording of "The Prince" and its B-side "Madness", and the band's second and third singles: "One Step Beyond" and "My Girl". The title song was a cover of the B-side of the 1960s Prince Buster hit "Al Capone". One Step Beyond... stayed in the British charts for 78 weeks, peaking at number 2. After the release of "My Girl", the band felt that they had exhausted the material from One Step Beyond..., and did not want to release any more singles from the album. However, Dave Robinson, head of Stiff Records, disagreed. Eventually, a compromise was made, and the band decided to release an EP featuring one album track and three new tracks. The result was the Work Rest and Play EP, which was headlined by the song "Night Boat to Cairo", from the One Step Beyond album. The EP reached number 6 in the UK singles chart.  Live recordings of Madness performances as well as those by other 2 Tone bands were used in the documentary film and soundtrack album Dance Craze.  In 1980, the band's second album, Absolutely reached number 2 in the UK album charts. Absolutely spawned some of the band's biggest hits, most notably "Baggy Trousers", which peaked at number 3 in the UK singles chart. "Embarrassment" reached number 4 in the charts, and the instrumental song "The Return of the Los Palmas 7" climbed to number 7. Although the album reviews were generally less enthusiastic than those of One Step Beyond..., they were mostly positive. Robert Christgau gave the album a favourable B- grade, but Rolling Stone awarded the album just one out of five stars. Rolling Stone was particularly scathing of the ska revival in general, stating that "The Specials wasn't very good" and Madness were simply "the Blues Brothers with English accents".  A drama-documentary film entitled Take It or Leave It was released in 1981, featuring the band members playing themselves in a re-creation of their early days to the then-current period.  In 1981, the band's third studio album, 7, reached number 5 in the UK album charts and contained three hit singles: "Grey Day" (no. 4, April 1981), "Shut Up" (no. 7, September 1981), and "Cardiac Arrest" (no. 14, February 1982). In an article in 1979, Chris Foreman explained that the band's music would move with the times, and change styles as time goes on. This was shown to be the case, as unlike the two ska-filled, fast-paced albums that preceded it, 7 was something of a change in direction. Suggs' vocal performance changed significantly, and his strong accent from the previous albums had been watered down. The album strayed from the ska-influenced sound of One Step Beyond... and Absolutely, and moved towards a pop sound; a trend that continued with subsequent albums.  Near the end of 1981, Madness released one of their most recognised songs: a cover of Labi Siffre's 1971 hit "It Must Be Love". The song climbed to number 4 in the UK, and in 1983, the song peaked at number 33 in the US charts. In 1982, Madness released their only number 1 hit to date, "House of Fun", which they played live on the 1980s series The Young Ones, and also reached number 1 in the album charts with their first compilation, Complete Madness.  In November 1982, they released their fourth studio album, The Rise & Fall, which was well received in the UK, but did not get an American release. Instead, many of its songs were included on the US compilation Madness, including "Our House", which was their most internationally successful single to date. "Our House" reached number 5 in the UK music charts and number 7 in the US charts; it was also performed live on The Young Ones. Many reviewers compared The Rise & Fall to The Kinks' Village Green Preservation Society, and it is at times retrospectively considered a concept album. The album also featured "Primrose Hill", which was more similar to The Beatles song "Strawberry Fields Forever", containing similar psychedelic imagery and a layered arrangement.
Question: what was a number one hit for them?

Answer:
hit "It Must Be Love".