Strange to say, but the 2019 European parliament election could turn into one of the turning points of British political history.

You might think it is obvious, in a modern democracy, that voters should be engaged in shaping the most profound change in our country’s international relationships for more than 50 years. And that a single vote nearly three years ago does not provide a basis on which party politicians, most of whom voted against the policy anyway, can claim the right to exclude the voters from the process.

Both Labour and Conservatives rightly fear that the party duopoly will not survive a more honest engagement with voters

But that is not how the Westminster game is played. In that parallel universe, the priority is to protect the exclusive right of traditional parties to interpret the wishes of the electorate with only occasional reference to their actual views. Both Labour and Conservative frontbenches have colluded in the same conspiracy to “respect the result of the 2016 referendum” (that is, to conceal the truth about its consequences) because they rightly fear that their party duopoly will not survive a more honest engagement with voters.

The European parliament election is the opportunity to call time on this charade. Whatever your view on Brexit, decisions that shape our future need to be justified on their merits. It is not enough to assert blandly that they are all the unavoidable consequences of the 2016 referendum, in which few of them were even discussed.

When opinion polls consistently show that a majority of UK voters agree with John Major that Brexit is a “historic mistake”, our failure to discuss any of the issues properly represents a profound democratic deficit at the heart of our politics.

All voters are entitled to hear their points of view argued within their parliament. The fact that this patently does not happen leads directly to the belief on the part of a large part of the electorate that they are disenfranchised as losers whose views count for nothing.

Neither party has any plausible claim to represent a broad-based national view

The European election is an important opportunity for voters to engage with the questions raised by Brexit and record their view. As they do so, they should remember that they are participating in an election that the UK parliament wanted to cancel and it is not difficult to see why.

When the electorate voted to “take back control”, they were thinking less about the balance between London and Brussels and more about the balance between the communities they live in and the elites they read about. In that balance, Westminster is part of the problem, not part of the solution. By offering a different lens on the Brexit process, the European election is challenging Westminster and, in particular, it is challenging the party duopoly at Westminster.

I have spent my adult life in and around Westminster and always defended the party duopoly as part of the democratic infrastructure. Its role has been to present a realistic policy choice to the voters and provide a structure by which politicians can be called to account for the consequences of their actions.

Sadly, I no longer believe it performs either of these necessary roles. The Brexit malaise is not an exceptional event that has disrupted an otherwise successful system – it is merely the most egregious example of a long-term trend that has undermined both effective politics and effective government.

Neither the Labour party nor the Conservative party has any plausible claim to represent a broad-based national view. The Tory party has fallen progressively under the influence of an English nationalist outlook, at the same time as Labour has fallen for a traditional version of socialism. I do not challenge the legitimacy of either point of view or suggest that either should not be represented in parliament. I simply believe that their representation should be proportionate to their public support and I do not wish to be trapped in a party structure that prevents me from arguing vigorously against both.

I shall continue to describe myself, as I always have, as a liberal conservative, but I shall do so in future as a supporter of Change UK – the Independent Group, which I believe has become the natural home of those who regard themselves, as I do, as the heirs of Disraeli, Churchill, Macmillan and Heath.

Disraeli was the inspiration for the concept of one nation; Macmillan argued the case for the middle way; Churchill and Heath were both passionate advocates of the importance of recognising our common interests in Europe. I do not believe any of them would have countenanced the idea that Britain should imagine its interests are best served by removing itself from the European mainstream.

And all of them knew when it is necessary to break the bonds of party loyalty.