Frank Field was already one of Labour’s most independent-minded legislators – so much so, in fact, that he faced a no-confidence vote from his local association and prompted some to wonder why he was allowed to represent the party.

But the Birkenhead MP has beaten Momentum’s commissars to the punch, announcing this afternoon that he has resigned the Labour whip over not just the attempted purge and inappropriate conduct of other members but also the Party’s handling of the anti-Semitism scandal.

His full letter to Nick Brown, the Opposition chief whip, is reproduced below, but Field’s decision raises a couple of immediate points as Parliament prepares to return from recess to another season of knife-edge votes.

The first is how much this decision increases the pressure on other Labour MPs to follow him out of the PLP. Stephen Bush, writing in the New Statesman only last week, revealed that some MPs are already planning a breakaway and that even amongst the rest visceral antipathy to the idea of a split is on the wane for many.

Whilst it may be possible to contain Field as a special case on account of his broader conflict with the leadership, he has nonetheless set a standard when it comes to responding to Jeremy Corbyn’s anti-Semitism problem.

The second post worth noting is that there is now a pro-Brexit vote in the House of Commons which isn’t even notionally beholden to the Labour whip – and one which probably has more areas of agreement with the Conservatives than your typical Labour MP. Of course Field has not shown any difficulty defying the whip in any event, but with the Government winning life-or-death divisions by painfully narrow margins this will doubtless seem like a welcome break.

Below is his resignation letter:

“Dear Nick,

“I am writing with considerable sadness to inform you of my intention to sit as an Independent Labour Member of Parliament. I am resigning the whip for two principal reasons.

“The first centres on the latest example of Labour’s leadership becoming a force for anti-Semitism in British politics. The latest example, from last week, comes after a series of attempts by Jeremy to deny that past statements and actions by him were anti-Semitic. Britain fought the Second World War to banish these views from our politics, but that superhuman effort and success is now under huge and sustained internal attack. The leadership is doing nothing substantive to address this erosion of our core values. It saddens me to say that we are increasingly seen as a racist party. This issue alone compels me to resign the whip.

“The second reason is that a culture of intolerance, nastiness and intimidation now reigns in too many parts of the Party nationally and is sadly manifest within my own Constituency Labour Party (CLP) in Birkenhead. This is, I fear, just one example of a phenomenon that has tightened its grip on CLPs across the country and is being driven, in part, by members who in previous years would never have been able to claim Labour Party membership.

“My original submission to the party on a specific bullying issue goes back eighteen months. Many submissions have since come from me as well as from loyal Party members. No decisive action has been taken. At best, the Party’s failure to act on these numerous complaints about the thuggish conduct of some members demonstrates a wilful denial. At worst, it serves to legitimise appalling levels of bullying and intimidation of lifelong Labour supporters.

“You know that I wrote to the Labour Party nine months ago about the atrocious behaviour of the then councillor Louise Reecejones. That Ms Reecejones should not be a member of the Party, let alone represent us in public positions, has been underscored by decisions taken by Wirral Council.

“As you know, she was found guilty of using her position as a councillor to intimidate members of the public. She has refused to apologise properly for her behaviour, and for breaching the Council’s code of conduct, even though one of those on the receiving end of her attack has only now a precarious hold on their livelihood.

“The charge sheet against this individual’s suitability ever to hold office, let alone represent the Labour Party, has been detailed to you in separate correspondence. While she was withdrawn as a Council candidate in Wallasey, she has still been able to join the Party’s shortlist for another seat and continues to hold an official position within the local Party.

“I intend to continue to represent Birkenhead in Westminster, as I have had the honour to do so for almost 40 years, and I will continue to do so as an Independent Labour Member. I shall of course remain a Party member as I have been since 1960. The values I have espoused during this time will be same that will continue to govern my conduct and I also intend, providence willing, to represent those views when the next election is called.

“Few events would give me greater pleasure than to apply to the Parliamentary Labour Party for the whip. But great changes in the leadership’s stance on the issues outlined in this letter will need to take place before I will be able to do so.”