Frank Field has resigned the Labour whip in protest at the leadership’s “toleration of anti-Semitism” and a “culture of nastiness, bullying and intimidation” among grassroots members.

The veteran MP for Birkenhead will now sit as an Independent Labour member in the Commons and has not resigned his party membership.

In a letter to Nick Brown, the opposition chief whip, the work and pensions select committee chair said he had made the decision “with considerable sadness” and stated his intention to rejoin the parliamentary party in the future.

Field’s decision is not especially surprising. He first floated the idea of sitting as an Independent Labour MP in a New Statesman interview in the early months of Jeremy Corbyn’s leadership. His relationship with his local party on Merseyside, where colleagues say he is an infrequent visitor rather than a full-time constituency MP, has long been strained.

Last month its members passed a motion of no confidence in him after he voted with the government on a key amendment to the EU Withdrawal Bill, averting a humiliating defeat for Theresa May and a possible early general election.

A longstanding antipathy towards Field, who is among the most right-wing MPs in the PLP and was a key opponent of Militant, also endures from Labour’s internecine struggles on Merseyside in the 1980s. It is clear from his letter to Brown that personal disagreements he had locally played as much a part in his decision as Labour’s malaise nationally.

But the nature of his departure differs in several significant respects from that of John Woodcock, the only other Labour MP to have quit the PLP so far. Unlike Woodcock, who claimed an internal investigation into allegations of sexual harassment was rigged against him for factional purposes, and said Labour was unfit for government, Field remains a member of the party, although sources close to the leadership are claiming it is not possible to resign as a Labour MP and do so.

He has also made clear he would like to seek the whip again. Whether he ever will is another question entirely. It is likely that the bar he has set for doing so – “great changes in the leadership’s stance” on anti-Semitism and bullying by grassroots members – is too high to ever be met, or otherwise politically unquantifiable. Even if he did, Field, who is 76, is now an even bigger target for deselection than previously.

Nonetheless, his letter and its tone is a sign of things to come. It is written more in sorrow than anger and does not adopt the scorched earth tone of Woodcock or Corbynsceptic MPs who appear to be on their way out, like Ian Austin. The likelihood is that most of the resignations that are certain to follow will look like this.

In the meantime, Field's departure will trigger a new bout of factional infighting. Jeremy Corbyn said: “Jeremy Corbyn thanks Frank Field for his service to the Labour Party." A Labour source sought to downplay its significance, stressing that the majority of his letter cited local issues and claiming he had been looking for an excuse to resign "for some time".

Tom Watson, Corbyn's deputy, has already issued a thinly-veiled criticism of the leadership. "This is a serious loss to the party and I deeply regret Frank’s decision," he said. "It reflects both the deep divisions in the party and the sense of drift engulfing us. It is a major wake up call."

Read Frank Field's resignation letter in full