The former London mayor said the party faithful would "all rally behind" McDonnell if current leader Jeremy Corbyn was forced to stand down.

Livingstone, who worked with McDonnell at City Hall in the 1980s, said he was "serious" and "principled" and the right man for the job.

He made the claim on RTUK's News Thing, which will air on Friday night. Host Sam Delaney asked him whether he had any personal ambitions to replace Corbyn as Labour leader.