Sir Paul McCartney and estranged wife Heather Mills' have failed in their attempts to put on a "united front" for the sake of their daughter while holidaying in The Hamptons.The former Beatle sailed alone in his boat, named 'Linda' after his first wife, while Heather played pool in a nearby bar with a male friend yesterday. Paul, 65, and Heather, 39 - who split last May after a four-year-marriage - agreed to holiday in the fashionable resort at the same time so the custody arrangements of their three-year-old daughter, Beatrice, wouldn't be disrupted. A source said last week: "It won't be a conventional family holiday - there is still tension."Last month, it was claimed Paul will give Heather £70 million (U.S. $140 million) in their divorce settlement. He has reportedly agreed to give the former model a £15 million (U.S. $30 million) lump sum, along with a further £3.5 million (U.S. $7 million) every year until Beatrice turns 18. Paul is set to pay for Beatrice's schooling, travel, security and nannies.The divorce deal, which sees the couple share custody of Beatrice, is also said to include a clause banning either of them from speaking publicly about their failed marriage.