On May 23, London will have a chance to send a clear message that this overwhelmingly Remain city — the engine of the British economy — wants to see Brexit stopped. Every vote for the Liberal Democrats will be a vote to stop Brexit. We hope and expect to do well.

The fact that European elections are happening at all is testament to the dismal failure of Brexiteers to have any real plan for how to deliver what they promised. They now seek to blame Remainers for not “falling in line”, as though we should somehow have ceased to believe what we do because a narrow majority of others disagreed. Yet the real reason Brexit has been delayed — and may well be cancelled — is that those who advocate it cannot agree on what it should look like. The whole project has run into the sand, as it deserved to.

Liberal Democrats have always argued that the public should have the final say on any Brexit deal. When we first said it, much of the political establishment scoffed. In Parliament in those early days it felt much like opposing the Iraq War — we were barracked on all sides but we stood steadfast anyway. Today a People’s Vote is among the betting market’s favourite outcomes, as millions have joined in the campaign by signing petitions and marching on the streets of London. What Parliament cannot resolve, plainly the people should determine.

The opponents of Remain in these elections are manifold. There is a crowded field of parties supporting Brexit: Labour, the Conservatives, Ukip, the Brexit Party and a smattering of others. There is competition within the Remain camp too.

Personally, I regret that it has not been possible to present a united front in these elections with the other Remain parties. The rules governing elections made co-operation difficult though not impossible. But the goodwill that runs through regular private discussions hasn’t carried through to a common platform.

I have at least agreed this week with Change UK that we should have a pact to train our campaigning guns on a common enemy — Brexit and its proponents — rather than indulge in friendly fire on each other. But the danger is that a passive “agreement not to disagree” is inadequate. I had wanted to make progress on something more ambitious, not least to avoid the ludicrous spectacle of a pro-Brexit Labour Party trying to assume the Remain mantle.

These elections may yet deliver shock therapy to the centre of British politics. A Financial Times analysis shows that a combined effort on today’s numbers would win 16 seats, whereas fighting separately the Lib-Dems would win seven, with the others getting nothing. While my own tribe might be happy to vanquish the other tanks on our lawn, nobody is so tribal that they believe seven to be a larger number than 16. And all sides will appreciate that if a failure to combine in European elections on proportional representation is counter-productive, failure to co-operate in first-past-the-post general elections could be even more damaging.

The reality that is not yet understood by newer players on the field is that fighting elections is not just about media coverage and political parties are not just about MPs. I am fortunate to have 10 excellent parliamentary colleagues in the House of Commons but more fortunate still that the Liberal Democrats have nearly 2,000 councillors (we hope more will be elected next week), and 100,000 members.

"We have a strong record on climate change, working within the EU to set targets for reducing emissions"

That infrastructure, alongside existing relationships with hundreds of thousands of voters, means we can run the most organised pro-Remain campaign, in which we hope to win over substantial chunks of dismayed and disillusioned former Labour and Conservative supporters.

A strong crop of Liberal Democrat MEPs will demonstrate not only rapidly changing opinions in the country on Brexit but will also be a strong endorsement of our wider platform. Being in the European Union is not just an end in itself but a prerequisite to the strong economy Britain needs to fund good public services. In particular, I want to see education elevated once again as the primary political issue of our time. That means not only giving children the strongest possible start but also making sure learning can continue through life, preparing people for working lives in which they pursue not just multiple jobs but multiple careers too.

Meanwhile, I met climate activist Greta Thunberg in Parliament this week. She challenged all the opposition on what they have done and what they would do. Liberal Democrats have a strong track record on climate change, working within the EU to set ambitious, cross-European targets for reducing emissions; creating thousands of green jobs in supply chains for renewables; tripling production of clean electricity; and setting up the Green Investment Bank. A Liberal Democrat vote is a vote for faster and more radical action to tackle the climate emergency.

When the elections have concluded, the centre of British politics must regroup. As the Liberal Democrats launch its campaign for the European Parliament today, our message is crystal clear: we can stop Brexit, and we must. The next common objective is to break the old two-party system. Doing so will require more than general goodwill but specific action. Each group would have battles to fight within their own organisations to make it happen, and these can be both bruising and time-consuming. But the prize for voters and the country would surely be worth the effort.