One of the most quoted pieces of folk wisdom is that “voters don’t like divided parties”.

The implication is that a political party which can’t keep its own house in order is unlikely to be trusted to run the country.

This month epic disunity has been on display in both the government and the opposition.

Bitter divisions have become almost routine among Conservative MPs, as they have dethroned and installed five leaders and prime ministers in just eight years.

Division in Tory ranks has undoubtedly been an electoral asset for Labour, helping to explain its massive lead in opinion polls. Now there are fears on the opposition side that heartfelt disagreements over the man-made humanitarian crisis in the Middle East could start pulling down Labour as well.

A new high pitch of vituperation in the Tory party was hit when the prime minister sacked his home secretary.

Suella Braverman slashed back at Rishi Sunak with a diatribe which included the phrases “uncertain”, “weak”, irresponsibility”, “magical thinking”, “betrayal” and “manifestly and repeatedly failed to deliver”.

It was sharpened with the ominous wake-up call that Sunak was “rejected by a majority of party members during the summer leadership contest” and therefore had “no personal mandate to be prime minister”.

Two outspoken female Conservative MPs – Miriam Cates and Dame Andrea Jenkyns – added to the tension by asking for a ballot to express no confidence in Sunak.

Some 40 Tory MPs stirred up the internal party debate further by putting their names to a parliamentary measure paving the way to Braverman’s preferred cause of resiling from the European Convention on Human Rights.

Meanwhile, Sir Keir Starmer suffered the worst parliamentary rebellion since he was elected Labour leader in 2020.

Some 56 of his MPs defied the party whip to vote for an immediate ceasefire in the conflict between Israel and Hamas.

As a result, 10 people were automatically sacked from his front bench team, although all the shadow cabinet remained loyal and kept their jobs.

The Labour revolt was a token gesture on a matter of principle. In practice, it could not change what happens in the Middle East.

Neither the Israeli nor Hamas leadership will take any notice of what the opposition in the British parliament is saying about their conduct of war. Especially since the ceasefire amendment, put forward by the SNP, was heavily defeated by 293 to 125.

In keeping with the dreadful death toll in Israel, Gaza and the West Bank, the mood in the Labour Party is sombre but free of the mutual recriminations so prevalent in Conservative ranks.

Shadow cabinet members were making no secret of their distress at talented colleagues sacrificing potential future ministerial careers.

For senior figures it is not the first time they have confronted divided loyalties.

For example, in 2005 Tony Blair suffered a major defeat when the Commons rejected his attempt to introduce 90-day detention for terror suspects.

The punishment for some Labour rebels was five years’ purgatory for their ministerial ambitions.

In spite of his disciplinarian reputation, Starmer has not so far been so strict as Blair.

Four of the middle-ranking ministers who quit on Wednesday only got the chance to do so because they were reinstated after previously rebelling in October 2020 against authorisation for so-called undercover “spy cops” to break the law.

Labour’s revolt might have been bigger if members of the shadow cabinet did not have more than a whiff of general election victory and real power in their nostrils. Few want to miss out on a share in that.

They also know that it is important to send out the signal to the electorate that they are united and ready to share the burdens of office, including difficult decisions.

John Healey, the shadow defence secretary, put his finger on this in his media round on Thursday, repeatedly stressing: “We are behaving as we would in government, we are not a protest movement.”

The New Labour government’s decision to go to war in Iraq has long haunted the party because of the failure to find weapons of mass destruction and its disastrous consequences in the region.

Ironically Starmer has now got his party into a similar state of agreeing to disagree on the current Middle East controversy – close to the Conservative position, but without the passion and internal party strife.

Back in March 2003, the vote to “use all means necessary to ensure the disarmament of Iraq’s weapons of mass destruction” was genuinely consequential.

Prime Minister Blair had committed to be bound by the outcome, even though he was not legally obliged to secure backing from parliament before entering a war.

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His government prevailed, by 412 to 125, only thanks to Tory party support. Eighty-four Labour MPs rebelled. Two ministers, Robin Cook and Clare Short, resigned from the cabinet.

Fallout from the Iraq invasion lay behind Labour’s move to the left in the 2010s.

A war-weary Ed Miliband broke with defence bipartisanship to inflict one of the major foreign policy setbacks of David Cameron’s premiership, by defeating the PM’s call to punish President Bashar al Assad militarily for the use of chemical weapons in Syria.

In 2015, Jeremy Corbyn, a prominent member of the Stop the War Coalition, was elected party leader.

In this decade Starmer has taken Labour in the opposite direction. His no-tolerance approach to perceived left-wing antisemitism resulted in the suspension of Corbyn and his close allies Diane Abbott and Andy McDonald, so disbarring them from standing again as Labour candidates.

The resignations over a ceasefire mean that there are now no members of the Socialist Campaign Group in Starmer’s campaign team.

It is possible that disagreement over Israel-Hamas could turn into a debilitating sore in the Labour Party.

It is more likely that internal arguments will be overtaken by events. Key UK allies, including the US and France, are pressurising Israel to show restraint while, by some analyses, it could complete its military objectives in a matter of weeks.

In her resignation letter, former shadow Home Office minister Jess Phillips spoke for many of the Labour MPs who backed the ceasefire amendment, saying “I must vote with my constituents, my head, and my heart” but she stressed she did not feel she was rebelling against Starmer.

Rebelling may make it easier locally for some of the 56 to retain their seats at the election.

This could offset the handful of constituencies – such as in Bristol and Brighton – where Labour’s more moderate official stance could cost it support to the Greens.

In all, the impact of Labour’s disagreement has been modest so far.

Older, more centrist voters may be attracted by Starmer’s resistance to pro-Palestinian pressure. In polls taken since the conflict broke out, two-thirds of Muslim voters are continuing to support Labour and the party’s lead in voting preference is still around 20%.

Meanwhile Braverman’s histrionics and the consequent cabinet reshuffle have distracted public attention from Labour’s agonising over the marches and the ceasefire vote.

Sunak continued his awkward straddle between red wall and blue wall Tories by appointing both the socially liberal David Cameron and GB News’ Esther McVey, as an anti-woke “minister for common sense”.

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Tory MPs, including party officials and former cabinet ministers, are continuing to argue the toss openly with each other over a wide range of policy and personnel issues.

The voters appear to have registered the different levels of disunity in both parties.

An Opinium poll this month asked whether voters agreed or disagreed that the parties were united.

Labour’s ratings were down significantly from a month earlier, from a net positive of +12 to -8.

Unsurprisingly polling for the Conservatives, who are not divided over Gaza, changed less since October.

For them the damage of disunity has already been done elsewhere on other matters. The Conservative Party’s net disunity rating worsened by just three points this month to an Arctic chill of -43.