Mullally's journalism career began in India where, from 1937 to 1949, he was sub-editor on The Statesman of Calcutta, then editor of the Sunday Standard of Bombay.
Back in London he worked as a sub-editor of The Financial News, as co-editor of the weekly Tribune,[1] and finally as political editor and columnist of the Sunday Pictorial.
From 1950 to 1955, he headed the public relations firm of Mullally & Warner, with clients ranging from Audrey Hepburn and Frank Sinatra to Douglas Fairbanks Jr., Paul Getty, Frankie Laine, the Festival Ballet and Picture Post.
In 1956, he was the only person to receive an interview with the newly married Prince Rainier of Monaco and his new wife, Grace Kelly, then on their honeymoon on the Prince's yacht while anchored off the Mediterranean island of Ibiza, a request granted to Mullally as, apart from being a resident of the island himself, he had been the only one of a pack of journalists to show appropriate respect for the feelings of the couple on their special occasion.
Between books, Mullally compiled and wrote with the collaboration with the BBC an album, The Sounds of Time a dramatised history of Britain (1933–45) and the long running Penthouse magazine's erotic strip cartoon "Oh Wicked Wanda!".