A few weeks ago there were suggestions that Jeremy Corbyn’s team had barred Ken Livingstone from the airwaves.

No ban was in evidence, however, as the former London mayor toured broadcasting studios leaving more controversy in his wake with every interview.

But the reports did reveal an increasingly strained relationship between the old allies - even before Mr Livingstone's Hitler comments.

The two have been friendly for decades and Mr Livingstone was a vocal advocate for Mr Corbyn during Labour's leadership race.

But in recent months there were claims that 'Red Ken' had become a "loose cannon" and complaints he was heading a rival camp against the shadow chancellor John McDonnell.

Many Labour MPs were outraged when it was emerged that he would co-chair the party’s Trident review and furious when he went on television to suggest it could recommend leaving Nato.

He was eventually pushed out of the probe, following fears that Mr Livingstone himself was “becoming the story”.

This latest row is not the first time Mr Livingstone has courted controversy – or been embroiled in an anti-Semitism row.

In 2006 a judge said he had made "unnecessarily offensive" and "indefensible" remarks likening a Jewish reporter Oliver Finegold to a Nazi concentration camp guard, although he was cleared of bringing the mayor’s office into disrepute.

The 70-year-old joined Labour in 1969, and by 1974 was on the Greater London Council, where he raised eyebrows by, among other things, supporting Sinn Fein's leaders at the height of the IRA's bombing campaign.

After Thatcher abolished the GLC, he was an MP between 1987 and 2001 sitting on the backbenches alongside his fellow left-winger and New Labour critic Jeremy Corbyn.