Former Labour leader Ed Miliband publicly joined forces with his successor Jeremy Corbyn for the first time since he took over the party to make the case for a Remain vote to show “solidarity” with the European Union.
At a rally in Doncaster, where Mr Miliband is an MP, the former leader urged Labour voters to think of the message that Brexit would send to the rest of Europe.
He highlighted the Labour movement’s historic links with the continent, stretching back to the fights against fascism in the Spanish Civil War and Second World War.
Mr Corbyn highlighted the EU’s role in green policies, saying that measures to protect the environment could not be effective within national borders.
Mr Miliband said: “We stand for remaining in the European Union for a very simple reason: we want a Labour government as soon as possible, but that Labour government will find it much easier to change this country and make it a fairer country if we are inside and not outside the EU.
“Think of all the issues we face: trade with other countries, climate change, making companies pay their taxes – every single issue we are stronger working with others than we are on our own.”
He added: “Throughout our history as a party – the Spanish Civil War, the Second World War – we have shown solidarity.
“Think of what our partners across Europe would say if we, the Labour Party were not in favour of remaining in the EU – we, the party of solidarity.
“So today we stand for solidarity again, we stand for staying in the EU.”
Mr Miliband said young people “take for granted the ability to travel across borders, to work elsewhere, to study elsewhere – think of their future, put their future first”.
Mr Corbyn said: “You can’t protect the environment just within national borders.”
Ahead of the joint appearance, Mr Corbyn said Brexit would threaten the effort to tackle climate change and protect natural beauty spots.
He said: “Climate change is one of the greatest fights of our generation, and at a time when the Government has scrapped funding for green projects, it is vital that we remain in the EU so we can keep accessing valuable funding streams to protect our environment.
“Leaving the EU would mean the green spaces, clean beaches and fresh air we want to leave for our children could be at risk. It would risk investment in new green technologies and the jobs that accompany them, and would leave us open to the Tory agenda which has been so damaging to our environment.
“Pollution and climate change don’t respect national borders so we can’t hope to deal with these issues if we withdraw into our shell. We must vote to Remain and continue to work with our European neighbours to stop climate change and protect our environment.”