There are a lot of people who at some point supported Jeremy Corbyn, but are now saying ‘with a heavy heart’ – always with a heavy heart – that he has to go. I would like to ask them to think one more time about this: to ask themselves why they supported him in the first place, and what has changed.

As soon as Ed Miliband was elected Labour leader in 2010, political commentators argued he had only won because of the 'union vote'. (In the final round of voting, Miliband won 46.6 per cent of MPs’ votes, 45.6 per cent of party members, and 59.8 per cent of affiliated union members.) The line was repeated over and over by Tory frontbenchers. In 2013, David Cameron told Miliband that the unions 'own you, lock, stock and block vote', even though John Smith had abolished the union block vote in 1993.

A lot of journalists (and others) have been calling Jeremy Corbyn a dinosaur. They should beware of the label. At the turn of the 20th century, the dominant political discourse – at least in what today would be called the ‘Westminster bubble’ – was that liberalism was passé, that the future lay with great empires and imperialist societies, and that anti-imperialists were doomed to ossify. ‘Imperialism’ infected all political parties, including the ‘Lib-Imp’ wing of the Liberal party, and even some Labour MPs. Yet within five years of E.T. Reed’s depiction in Punch in 1900 of the remaining Liberal anti-imperialists of his time (shown here), imperialism had lost its attraction to voters, the ‘imperialist’ party was hammered in an election, and a new, quite old-fashioned looking Liberal government came to power.

‘Does it look big?’ an elderly woman asked me, craning her neck to see down the street. ‘I’m afraid so,’ I replied, thinking she might be worried about getting to the Tube. ‘Good,’ she said. Like thousands of others, she was in London on Saturday for the national anti-austerity demonstration organised by the People’s Assembly. As we marched from the Bank of England to Parliament Square, the crowd kept growing.

A few weeks ago, it seemed impossible that a socialist would be in the running for the Labour leadership. The former miners’ leader Ian Lavery had ruled himself out and supported Andy Burnham; Lisa Nandy had resisted attempts to ‘draft’ her into the race. The debate was firmly anchored to the right, with Ed Miliband under attack for being ‘anti-business’ and focusing on the disenfranchised.