The JC can reveal that the Labour Party inquiry announced this evening into racism – including antisemitism – was set up after a serious dispute between the offices of John McDonnell, the Shadow Chancellor and Jeremy Corbyn.

The inquiry, which is to be chaired by Shami Chakrabarti, was suggested by a senior member of Mr McDonnell’s staff as a response to this week’s suspensions of Naz Shah and Ken Livingstone. The idea was taken up by the Shadow Chancellor and proposed to Mr Corbyn as a serious attempt to deal with the problem of antisemitism within the Labour Party and the widespread perception that Mr Corbyn was soft on the issue.

On Friday afternoon, rumours began to spread that at least two Shadow Cabinet members had threatened to resign in protest at Mr Corbyn’s lack of interest in dealing with antisemtism.

They were angry that he had initially dismissed the idea of suspending Ms Shah, issuing a statement saying simply that he had spoken to the MP for Bradford West. It was only after pressure from Labour MPs that she was later suspended.

On Thursday, reports circulated around Westminster that while Mr Livingstone was speaking on the BBC Daily Politics programme, Seumas Milne, Jeremy Corbyn’s director of communications, had remarked that the former Mayor of London "had a point" and that he should not be suspended.

By this afternoon, the lack of any further action or serious statement from Mr Corbyn after this week's suspensions was said to be pushing some Shadow Cabinet members towards resignation.

Meanwhile, the JC understands that the idea of an inquiry and recommendations from an independent source was being resisted both by Mr Milne and Simon Fletcher, Mr Corbyn’s chief of staff – who for 12 years previously was Ken Livingstone’s senior adviser. Both are believed to maintain that there is no problem of antisemitism within the Labour Party and that this week’s events are a smokescreen for Mr Corbyn’s enemies to plot against him.

By late afternoon today, staff in Mr McDonnell’s office believed that the inquiry proposal had been killed off by the leader’s office. But a combination of further pressure from Mr McDonnell directly to Mr Corbyn, and the fear that imminent Shadow Cabinet resignations could prove fatal to Mr Corbyn’s leadership, led to the decision to set up the inquiry, announced earlier tonight.