In Parliament Square

‘Some people are going to have a problem with that flag,’ a man said to me as we marched down Piccadilly on Saturday. He was talking about the flag of the Syrian National Coalition: green, white and black, with three red stars. A Syrian refugee recently arrived in Britain, he said the flag didn't represent Christians or Kurds, and that he hoped the protesters 'support all civilians'.

The Solidarity with Refugees demonstration was organised by Ros Ereira and Abdulaziz Almashi, who set it up on Facebook in the run-up to today's emergency EU meeting on the refugee crisis. Supported by the Syria Solidarity Movement, Refugee Action, Amnesty International, Stop the War Coalition and others, the march drew tens of thousands of people in London. The message for Theresa May to take to Brussels was that 'we can’t continue to allow thousands to die trying to reach the EU'. People chanted: 'Say it loud, say it clear: refugees are welcome here.' The slogans included 'End detention, end fast track' and '20,000: are you joking?' – referring to the number of refugees David Cameron has promised to allow into the UK. That amounts to six per constituency per year. Posters compared the number of refugees per capita taken in by Britain and other European countries. One banner said: 'Germany 1 – Britain 0'. (This was before Germany closed its borders.)

When the news came of Jeremy Corbyn's victory in the Labour leadership election, the crowd cheered. Kamal Majid, an Iraqi Kurd and a vice president of Stop the War, told me he was there to show support for his friend Corbyn. An Iraqi woman carried a poster that said: 'We are one, there is no “Other”.' She told me she had a problem with flags: 'They're all about “my tribe, my country”.'

At Trafalgar Square the protesters were joined by National Gallery staff, still on their anti-privatisation strike. Next stop was Downing Street. I saw a banner with the famous sentences from Donne’s Meditation 17 ('No man is an island... It tolls for thee'). Next to it was a shorter one: 'Refugees in, Tories out’. 'Politics is about right and wrong,’ a woman said, ‘and this is wrong.' She was talking about austerity.

Legal Action for Women distributed leaflets advising asylum seekers on ways to avoid deportation. Protesters talked of recent trips to Calais to deliver aid, others of their willingness to take in refugees. MyRefuge is setting up a platform for 'an AirBnB for refugees' that will allow them 'to directly connect with a global community of people who want to open their homes and communities to them’.

At the rally in Parliament Square, many of the speakers congratulated everyone on Corbyn's win. Diane Abbott said that 'asylums seekers couldn't have hoped for a better supporter'. Walter Wolfgang, the vice president of CND, talked of being a refugee in Britain in 1937. His colleagues from Stop the War warned that 'bombing Syria won't ease the plight of refugees'. Natalie Bennett, the leader of the Green Party, formulated the protesters' main demands for the government: to take 'our fair share of refugees in Europe' and to develop an 'orderly resettlement programme'.

Corbyn came on stage to cheers of 'Jez we can!' He thanked 'ordinary people' in Hungary and Austria who were giving support to recent arrivals. Talking about the causes of the crisis, he said that 'our objective ought to be to find peaceful solutions' to alleviate them. 'We as ordinary decent people say to our government,' he began, then paused for breath. Someone in the crowd shouted: 'Fuck the Tories!' Corbyn finished: 'Open your hearts and open your minds and open your attitude towards supporting people who are desperate.' Billy Bragg sang ‘The Red Flag’, and people in the crowd waved them.