The former director of London Jewish Forum and current national secretary of the Jewish Labour Movement has been elected to the powerful Labour Party committee which will decide the fate of Ken Livingstone.

Peter Mason, a Jewish councillor in Ealing, was elected to Labour’s influential 11-member National Constitutional Committee, which has power to expel London’s former mayor from the party, its decisions being final.

It is the first time that a JLM candidate has been elected to a national committee in 20 years, and comes after a report by former Liberty director Shami Chakrabarti recommended a transfer of powers to the NCC.

Livingstone, who appeared before the Home Affairs Select Committee two weeks ago, is likely to have his party membership cancelled for comments he made on radio, in which he called Adolf Hitler “a Zionist”.

On 30 June, Mason tweeted: “Given the findings of the Chakrabarti Report, Ken Livingstone’s continued membership of the party is no longer tenable.”

Days later, he branded as “insane” Labour leader Jeremy Corbyn’s comment that Diaspora Jews are no more responsible for Israeli government actions than British Muslims are for so-called Islamic state.

Livingstone’s disciplinary has already started, but while Mason is not due to start until September, it is understood that he will be in a position to input into the process informally.