Businessman and former chief of the Grand Prix Ron Walker has died from cancer aged 78. Mr Walker, the millionaire who played a key role in the creation of Melbourne’s Crown Casino, had battled the disease for years. He retired as chairman of the Australian Grand Prix Corporation in 2015 after a 22-year stint. Mr Walker also served as the Lord Mayor of Melbourne from 1974 to 1976, and was the city's 2006 Commonwealth Games Corporation chairman. A prominent Liberal Party figure, he worked as national treasurer of the party from 1987 to 2002. Tributes are already flowing for Mr Walker on Twitter, with Prime Minister Malcolm Turnbull writing "we will not see his like again".