The Green Party wants to create a new bank holiday dedicated to the contribution migrants have made to the UK.
Members approved the new policy at their party conference in Harrogate on Monday, ahead of a speech by co-leader Jonathan Bartley.
It would see Windrush Day, which falls on June 22, officially marked as a national holiday. The date is widely acknowledged and regarded as significant - particularly among the Caribbean community - as it was the first time Commonwealth citizens from the Caribbean docked in the UK, at the request of the government, to help rebuild Britain after the Second World War.
Earlier this year the Greens called for a four-day working week to alleviate growing levels of stress and illness among workers.
Bartley, who job-shares his leadership position with the Greens’ only MP, Caroline Lucas, said: “In a political climate that has become increasingly hostile towards migrants, it is more important than ever that we speak up, cherish, and recognise the enormous contribution they have made to this country.
“Nothing can be done to completely right the historic wrongs that were inflicted on the travellers, the slaves, and the refugees who have come to Britain but we can use our influence today to make Britain a more welcoming and inclusive society tomorrow.”
When he began his speech, Bartley joked he was well-prepared, having come equipped with throat sweets, blu tack and “a vision for this country”, before telling members Greens will “pioneer a future in which we all have a stake”.
“The Green Party would give local people power to decide what happens to them and what gets spent where,” he said.
“Participatory budgeting. Putting financial power in people’s hands.
“With regional banks that invest in the kinds of bonds and shares and trusts that hold communities together. Creating strong resilient economies to withstand the winds of globalisation. The Green Party is the party of small business.
“Of creators, givers, sharers and contributors. Of the little guy. The social entrepreneur. The activist. The creative coder and the brave builders. The party for anyone who has a dream. For everyone that wants an economy working for them, not against them.”
Bartley called for foreign secretary Boris Johnson to be sacked, describing him as a “poison” at the heart of the Conservative Party.
“In many ways he is a joke. But then you listen to what he’s actually saying. Let’s not pretend that Boris Johnson’s comments about dead bodies in Libya was an aberration. It wasn’t,” he said.
“This is not new bigotry. It’s old. It’s unacceptable. And it’s time the Conservative party took collective responsibility for this human wrecking ball and kicked him out of the cabinet.”
Speaking to HuffPost UK after his speech, Bartley followed co-leader Caroline Lucas in calling for backbench MPs from both main parties to back the Greens’ proposal for a second public vote on the final Brexit deal.
“I would absolutely encourage other MPs to get behind our call for a ratification referendum.
“The British people have been lied to from way before the Brexit vote and the truth is still being kept from them now.
“The opinion polls show that more people are in favour of the Stop Brexit movement and we are taking our place within that.”