In an ideal democracy, it might be possible to treat the process that begins on Tuesday in the House of Commons as a worthy culmination of the long debate on Britain’s relationship with Europe after Brexit. For two days, MPs will examine many of the most difficult questions raised by Brexit as they look in detail at the Lords’ amendments to the EU withdrawal bill. Issues that have dominated politics for the past two years – such as the Irish border, the customs union, the single market, ministerial powers, EU law, fundamental rights, devolved powers and the final “meaningful” vote when the terms are known – will all come under the microscope.

Yet as Britain moves closer to leaving the EU at the end of March next year, there is no sense of an approaching closure or of a settled national will on any of these issues, let alone on the fundamental future relationship itself. In fact, Britain is as divided, conflicted and uncertain about its future as ever. None of the salient Brexit questions has been satisfactorily resolved, partly because the potential damage from them is so stark and interconnected, but also because the Conservative party – and to some extent Labour – have proved incapable of national leadership. Yet instead of reasoning about Brexit problems, the actions of hardline leavers have grown increasingly shocking. David Davis threatens to resign over a date. Boris Johnson suggests Donald Trump would have been a better negotiator. Liam Fox looks on as the White House upends his trade deal dreams. Meanwhile Jacob Rees-Mogg announces that customs checks are suddenly unnecessary.

But it is not just the main parties that are failing. So is the insurgent movement that caught the anti-political tide in the referendum two years ago. As Paul Dacre steps down, leaving the politicians to clean up the damage after the relentless reactionary campaigning of his Daily Mail years, the Cambridge Analytica and Leave.EU implosions illuminate the leave campaign’s dirty secrets. As MPs debate the bill, Leave.EU’s millionaire founder and bankroller, Arron Banks, will be telling a select committee about extensive contacts with Russian diplomats and trips to Moscow, where discussion included lucrative business deals, all during the Brexit campaign.

The Lib Dem leader, Vince Cable, was right to warn on Monday that the worst possible Brexit, a potentially catastrophic no-deal, now looks increasingly possible – just at the very moment when the G7 debacle shows the vital importance of international cooperation. The Brexit project is like a clapped-out car wobbling and wheezing towards the finishing line next year with wheels and bits of bodywork falling off as the line approaches. At just such a dismal moment, MPs face vital decisions about the country’s European links. The worry is that party interest means the debates and votes will not be worthy of the issues. Instead they could be all too glumly representative of the miserable domestic political shambles of the past two years. But there is still time to dump the car.