Inflatable pigs could fly once more when Roger Waters rejoins David Gilmour and the rest of the group at Live 8 for his first performance with them since 1981.

The Who yesterday also joined a line-up that already includes Sir Paul McCartney, Sir Elton John, U2, Madonna and Coldplay.

The Times understands that Pink Floyd are rehearsing four songs for the July 2 concert, three of which will be taken from the 35-million selling 1973 album Dark Side of the Moon.

To get to this point, bassist Roger Waters, the creative force behind The Wall, has broken a 20-year silence to speak to his former schoolfriend David Gilmour, Pink Floyd’s guitarist and singer.

The four shareholders in Pink Floyd Music Ltd have conducted business via lawyers and faxes since Waters sued his colleagues for continuing to use the band’s name when he walked out in 1985.

But at Geldof’s insistence, the acrimony will be forgotten for 20 minutes at Hyde Park in front of a global TV audience of millions. The Africa campaigner starred in a 1982 feature film of The Wall, and told the feuding duo that the band had to unite for Live 8.

A source said: “Bob played Cupid. He phoned Roger and sold him the gig. Then he communicated what Roger said to Gilmour. He relayed David’s response back to Roger.

Slowly they came to the same conclusion.” Gilmour is believed to have come on board as late as last Friday and told Nick Mason, the drummer, and Richard Wright, the keyboard player, that the reunion was on. Eventually Waters and Gilmour spoke directly to each other.

Geldof needed Pink Floyd to generate maximum interest in Live 8 in the United States, where Dark Side of the Moon spent a record 1,300 weeks on the charts. The band grossed £60 million on their last US tour, without Waters, in 1994.

Gilmour, who is said to be worth £60 million and recently gave the homeless charity Crisis the reported £4.5 million proceeds from selling his London house to Earl Spencer, said: “Any squabbles Roger and the band have had in the past are so petty in this context, and if reforming for this concert will help focus attention, then it’s got to be worthwhile.”

Syd Barrett, the “genius” founding guitarist who left the music business in the late 1960s after an LSD-induced mental breakdown, is not expected to return.

Despite this success, Geldof has still to convince the Spice Girls to reform. He has asked members of the group individually to resolve outstanding differences but a Live 8 appearance has yet to be confirmed.

• More than two million text messages were sent into the lottery to win tickets for Live 8, generating about £3 million for the appeal. The 66,500 winners, who will each receive two tickets, will be notified by text by Thursday.

  Meanwhile, another text message lottery opened yesterday for 50,000 tickets for the Edinburgh Live 8 concert, featuring Dido, Travis and Snow Patrol.

  FLOYD IN NUMBERS

  £60 million: ticket gross for 1994 last US tour

  35 million: global sales for 1973 opus Dark Side of the Moon

  17 million: The Wall (1979) total world sales

  10 million: Wish You Were Here (1975) world sales 6 million: Animals (1977)/A Momentary Lapse of Reason (1987) world sales

  591 consecutive weeks in the US chart for Dark Side of the Moon from 1973 to 1988

  15 consecutive weeks at US albums No 1 for The Wall

  10 number of years Waters says it takes Gilmour to write one song

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