Born in Florence but forever associated with a black-and-white post-war Britain, she began her career as a model for Vogue, and then worked as a continuity announcer for the BBC.
She went on to dip her toe into many other areas of the entertainment industry and was a frequent panellist on shows like What’s My Line? and Juke Box Jury at the BBC, for whom her English rose beauty – despite her Italian heritage – and her charm and cut-glass accent were a perfect fit.
When the Eurovision Song Contest began, she was the obvious choice as hostess, and her poise, unflappability and perfect French earned her many plaudits.
Perhaps her most notable performance was in Brighton in 1974, when a little-known Swedish foursome called Abba emerged triumphant.
Boyle also fronted the Ivor Novello Awards, and had a long-running programme called Katie and Friends on Radio 2.
She was also known as an agony aunt for TV Times and for writing a weekly column on fashion and beauty in the old Sunday Graphic.
A lover of dogs, she was a committee member of the Battersea Dogs Home for more than 25 years and wrote Battersea Tales, stories of rescues from the home, in 1997.
She married three times, retaining the surname Boyle from her first husband, Richard, heir to the eighth Earl of Shannon. Her last marriage, in 1979, was to the late producer of The Mousetrap, Sir Peter Saunders.
Boyle wrote about her life in showbiz in 1980 in autobiography, What This Katie Did.
In 1998, she said: “My whole career really started by accident. There was a time when I was on the BBC three times a week – it seems very strange to think of that now, but it was the only thing people watched.”