<human>: Brotherhood of Man are a British pop group who achieved success in the 1970s. They won the 1976 Eurovision Song Contest with "Save Your Kisses for Me". Created in 1969 by songwriter and record producer Tony Hiller, Brotherhood of Man was initially an umbrella title for a frequently-changing line-up of session singers. Early on, they scored a worldwide hit with the song "United We Stand".

Keen to keep the established name alive, Hiller set about putting a new line up together. In 1972 he got together a trio of session singers, Martin Lee, Nicky Stevens and Lee Sheriden.  Sheriden was already known to Hiller as a songwriter and had a solo career. Lee had a solo single to his name and was a budding songwriter. Stevens had been classically trained, but had since adapted her vocals and was performing as a cabaret singer. The trio began recording together, but their first single, "Rock Me Baby", to be released at the end of 1972, was cancelled due to the release of the song by David Cassidy. Finally their first two singles "Happy Ever After" and "Our World of Love" were released in 1973. Neither single charted and soon after, another female vocalist was added to the line up, Sandra Stevens. Stevens (no relation to Nicky) had been performing as a big-band singer since a teenager in the late 1960s. She had sung with the Joe Loss big band and alongside Eve Graham (of The New Seekers) in club group, The Nocturnes.  Now signed to the Pye spin off label, Dawn, the quartet released their first single, "When Love Catches Up on You" in January 1974. It failed to chart, but the follow-up single, "Lady" became a hit in Europe. Encouraged by this, the group set about recording their debut album. The album Good Things Happening was released later in the year along with two more singles, but none of these found success. Before the record label folded, Brotherhood of Man released one more single in the Summer of 1975. This was the upbeat "Kiss Me Kiss Your Baby" and although failed to make an impression in the UK, became a big hit in Europe, reaching Number one in Belgium and Number two in the Netherlands as well as top 10 placings in other countries. Brotherhood of Man toured extensively in Europe, honing their stage act and harmonies, while Hiller, Sheriden and Lee worked on composing songs for their second album. Among them was a song Sheriden had largely written called "Save Your Kisses for Me". CANNOTANSWER

Using a quote from the above article, answer the following question: How long did this current line up last?
<bot>: CANNOTANSWER