Sydney: Lady Sonia McMahon, the glamorous widow of former Australian prime minister Sir William McMahon and mother of Hollywood-based actor Julian, has died in Sydney, a hospital spokesman said on Saturday.
McMahon, who created headlines in 1971 when she wore a daring white dress with splits up both sides to a White House dinner with Richard Nixon, had been suffering from cancer.
"Lady Sonia McMahon passed away late last night," a spokesman for St Vincent`s Private Hospital said.
"She died peacefully with her family by her side."
McMahon worked as an occupational therapist before she married her husband -- who was 24 years her senior -- in 1965.
During her husband`s term as prime minister she attended a White House dinner held in his honour wearing a floor length gown slit to the thigh and held together from there to under the arm by thin rhinestone-studded straps.
Asked about the incident later, she said: "Well, there are worse things I could be remembered for, I guess."
"We used to go to continuous dinners and have to wear long dresses and I got so sick of all those ordinary sort of dresses that I thought, `Oh, I can`t stand it any more`, and so this was a light relief."
Prime Minister Kevin Rudd paid tribute to McMahon, describing her as a "distinguished representative of Australia".
The 77-year-old had been a fixture on Sydney`s social circuit until hit by skin cancer and other ailments over the past 18 months.
She is survived by her three children -- daughters Melinda and Deborah and actor son Julian, who played one of the lead roles on US television show "Nip/Tuck".
William McMahon was prime minister from 1971 to 1972 and although he retained his seat in Parliament until his retirement in 1982 he is remembered as one of the country`s least popular leaders. He died in 1988 aged 80.