Gordon Brown today makes a direct appeal to 24 million voters who supported Labour or opposed the Tories to back Britain’s membership of the EU in order to tackle worries over their family’s prosperity.

The former prime minister said he was asking non-Tory voters, “many of whom feel economically insecure”, to vote to stay in the EU because of the prospect of 500,000 new jobs, cuts in energy bills and tougher action on terrorism and people smuggling.

The speech, at the Fabian Society’s summer conference in London, is Brown’s latest intervention in the referendum campaign and comes as the Vote Leave camp looks increasingly bad-tempered amid signs they are falling behind in public support. An IPSOS Mori survey published in the London Evening Standard on Wednesday showed an 18 point lead for the Remain camp.

Today Brown – who delivered a series of barnstorming speeches to help win the Scotland referendum – will seek to capitalise on the In campaign’s momentum by arguing Britain’s future it to “join in Europe to lead in the world”.

“I am speaking directly to the UK’s nine million plus Labour voters and the 15million voters who would not vote Conservative, many of whom feel economically insecure, think the status quo does not work for them and believe they have lost out from wave after crushing wave of global economic restructuring. They want to know how Europe will deliver for them in the future,” he is expected to say.

He will go on to urge young people to sign-up to vote before the registration deadline on June 7. A Hope Not Hate survey published by Brown today shows Labour supporters aged between 18 and 30 want to stay in the EU by a four to one margin.

“While the Scottish referendum saw an 85 per cent turnout, a general election style turnout of around 66 per cent would mean 15 million potential voters remaining at home.

“It is important to point out the costs of leaving Europe and to expose the weaknesses of the alternatives advanced by Brexiteers, but Labour voters who do not feel the status quo works for them and yearn for a better future also want to hear all of the positive reasons for voting to remain.

“The modern challenge for our country – like all others – is to get the balance right between the national autonomy we desire and the international co-operation we need.”

Brown uses his speech to pick out several key areas to demonstrate the “positive, practical and progressive” benefits of EU membership, including: