The row continued off-air when a furious Mr Johnson swore at his Labour opponent.
Travelling up to the roof terrace to be photographed, the Mayor shouted at Mr Livingstone "it's all f****** lies, it's all f****** lies".
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Oliver Letwin MP, who was in charge of Brexit negotiations for two weeks, tells ITV News what he thinks will be easy and what will be hard.
Theresa May's decision to delay green-lighting Hinkley nuclear plant has put noses out of joint. But EDF is confident it will go ahead.
Highs of 23C at best in the afternoon sunshine but feeling cooler in the mornings and the evenings.