It has been a terrible few weeks for centre-left politics in the UK, with the horrific murder of Jo Cox MP, the loss of the referendum and now the undignified spectacle of Jeremy Corbyn clinging onto the leadership despite pressure from across the whole of the mainstream of the Labour Party for him to accept his part in the culpability for the defeat and step down.

It is absolutely vital that Labour changes leader and the party is able to offer credible and mainstream leadership to a divided and shaken country in the face of the national crisis caused by the Brexit vote. If an early General Election is called in October with Corbyn as leader we could lose large numbers of seats. With a refreshed leadership and the party able to unite behind someone strong and credible, we might return to power and the responsibility of leading Britain out of this crisis.

The referendum was a catastrophic defeat for progressive politics in Britain. It happened on Jeremy Corbyn’s watch and he must bear his share of responsibility just as anyone would if a disaster of similar magnitude happened on a project they were responsible for.

We saw Jeremy’s half-hearted and uninspiring campaigning over the last month. We saw his bizarre judgement in emphasising the issue of freedom of movement when this was the very issue that was most alienating working class Labour voters in the North and Midlands.

Unless we want to lose Labour safe seats to UKIP we cannot risk a repeat performance in a snap General Election.

We have to unite behind one leadership challenger, whoever is best placed to end the failed experiment that Jeremy Corbyn and John McDonnell have led, unite the party and take the fight to the Tories in a snap General Election as a credible alternative Prime Minister.

Now more than ever Britain needs the Labour values which were notable only by their absence in the referendum campaign.

Now more than ever Labour needs a new leader who can stand up for those values in Parliament, in negotiations with the EU and the remaining 27 member states, and in Downing Street after the coming election.

And now more than ever we need mainstream Labour supporters to sign up as party members, stand up for their values and elect a new Leader.

Anyone who is devastated by the referendum result and wants to take a step back on the road to serious, progressive politics should now join the Labour Party.

A leadership election is looming and, while Jeremy Corbyn has lost a lot of support among party members in the last few months, we need more to join us if we are to elect a mainstream, credible Leader.

If there is a contested leadership ballot we need to counteract the mass recruitment of Corbyn supporters that happened last year not just by persuading the wing of his previous voters who have been alienated by incompetence, sectarianism, failure to make electoral headway and what increasingly looks like the deliberate sabotage of the Labour In campaign to switch, but also by recruiting hundreds of thousands of new members and supporters ourselves.

All that energy and desire for change in our politics apparent from the referendum campaign and the reaction to it needs to be channelled into a concerted membership drive across every town and city in our country.

Labour is the party of the many, not the few.

And now is our chance to show that the mainstream are many and the far left are few.