Goodbye to this most remarkable of parliaments, dissolving all too aptly on Guy Fawkes night. For all the extremes of abuse hurled at them, it has harboured the bravest and best MPs, who have broken ranks to defend the country against a Brexit disaster, putting conscience and honour before party, tribe or personal career. This departing Commons should be remembered as the parliament of conscience.

These MPs were fortunate in a Speaker who rose to the great constitutional crisis with the vision and effrontery to break traditions, to protect parliament’s sovereignty against an overreaching executive. With no Commons majority, Theresa May and Boris Johnson summoned unprecedented Henry VIII powers to try to sneak in shedloads of crucial legislation by statutory instrument, without votes. If taking back control was the purpose of Brexit, John Bercow seized it on behalf of citizens.

Traditionally, people say they want MPs to speak their minds, not blindly follow party whips. Look how many MPs broke free. May lost an unheard-of 33 votes in the Commons, Johnson has already lost 12. In ministerial resignations, 36 walked out on May – including Johnson, who has already lost two.

Our first past the post system grinds up most who dare leave the rigid bondage of the two-and-half main English parties

Even more momentous, an unprecedented 89 MPs left their parties, voluntarily or ejected. Johnson the autocrat purged 21 of his moderate MPs, including distinguished ex-chancellors and brightest sparks, causing most of their One Nation club to stand down tomorrow. Remember that purge whenever Johnson poses as a one-nationer.

This parliament, says Gavin Freeguard of the Institute for Government, has seen its greatest cracking of the parties: only 28 Labour MPs split to form the SDP in 1981. If Change UK defectors were disappointed that their defections didn’t set off a system-breaking avalanche, their insignificance did act as a deterrent: our abominable first-past-the-post system grinds up most who dare leave the rigid bondage of the two-and-half main English parties. Tory rebels Dominic Grieve or Anna Soubry standing as independents in their old seats defy gigantic odds. But in a fair voting system, it shouldn’t be so.

Shining lights in this departing parliament include many such as Oliver Letwin, who defied their parties to ensure a vote on the great question of our generation. How shaming it looks that May initially wanted to Brexit with no Commons vote on her final deal. Rebellions on all sides were driven by conscience: Mark Francois and his European Research Group are greeted as “raving lunatics” by those they in turn dub “remainiacs”, but there’s no doubting their sincerity. Nobody could accuse those such as Caroline Flint – who choose to obey their leave constituents – of a lack of conviction.

However, any parliament has its quota of bounders and greasy pole-vaulters: Matt Hancock and Jeremy Hunt swivelled from remain to hardest leave in their leadership bids. Too many Tory remainers stayed silent, imposing on the country a leader they know is unfit, hoping Johnson will save their jobs. Some Labour shadow spokespeople, with their eye on post-Corbyn times, parrot a party line on Brexit neutrality they can’t possibly believe – though bolder voices loudly proclaim for remain against orders.

If this parliament looked like deadlocked purgatory, the Commons has rarely better reflected the national state of mind. The country is split, conflicted, afraid to defy the referendum, to revoke it or carry it out. That is who we are: angry, anxious, stuck. But a “firm government” with only minority support would be no answer. Cameron’s 2015 government, elected by just 36% of the people, stampeded through a referendum that has destroyed us. Let that be the last time. Brexit makes the case for electoral reform unanswerable.

With the most volatile electorate on record, people are thrashing against this lack of choice. YouGov reports 37% will reject the two main parties, but most risk wasting their votes. There is only Johnson, Jeremy Corbyn or Jo Swinson, take it or leave it. The Tory press begs voters to shun Farage’s party or lose Brexit. Remainers need one in three of the electorate to vote tactically, so Corbyn-detesting Liberal Democrats must vote Labour, and passionate Corbynistas must vote Lib Dem in winnable seats. Let’s hope they do.

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It’s a monstrous system that denies people the right to vote for their true feelings. Many want to vote Green in this climate crisis, but are denied. Last time, 68% of votes were utterly wasted, lost in those rotten boroughs called safe seats. Parties would think differently if they had representation in every region. Tories are adrift in much of the north (look at their patronising expedition to Workington). Yet last time they got 34% of the north-east vote, but only 9% of the seats. Labour is all but excluded from the south-east, its 29% vote gaining only 10% of seats.

With Scotland gone, psephologists judge a hung parliament the best Labour can hope for – and a good thing, too. Compromise and negotiation between parties in hung parliaments is a better path, given the divided country. An outright majority for Johnson is a terrifying prospect – free to do anything, with his party’s moderates purged, despite only minority support.

Labour’s leadership could add electoral reform to the party manifesto and trounce critics by proving themselves to be open democrats, not tight party conspirators – willing to collaborate with others. (Since Lib Dems would make it inevitable, why not take the credit?) John McDonnell is just one of Labour’s many proportional representation supporters. The Hansard Society warns: “The public reputation of parliament and MPs is at a nadir.” The best hope is for a hung parliament – and a new Speaker brave enough to encourage a convention on voting reform.

• Polly Toynbee is a Guardian columnist