Gordon Brown urges mothers to back EU for children's sake

Gordon Brown will call on voters to remain in the UK. Picture: Greg Macvean

Around 500,000 new jobs can be created by opening up the single market further to British firms, according to the former prime minister.

Environmental co-operation across the 28-member bloc could lead to cuts in energy bills and Brussels has boosted protections for workers, he will also insist.

The EU is leading the way in rooting out tax havens and links between British and European forces are helping to stamp out terrorism, people-smuggling and trafficking, the former premier will tell the Fabian Society summer conference.

Meanwhile Justice Secretary Michael Gove warned that a migrant influx equivalent to the population of Scotland will put “unsustainable” pressure on the NHS by 2030 unless Britain quits the EU.

The Cabinet heavyweight insisted the worst-case scenario figure of 5,229,000 more net migrants over the next 15 years was realistic, even though it assumes Turkey, Albania, Serbia, Montenegro, and the Former Yugoslav Republic of Macedonia, will join the EU in 2020, and the UK will not impose transitional immigration controls on them.

Attempting to push immigration to the heart of the referendum campaign, Mr Gove insisted the national living wage would act as a pull factor resulting in “huge additional pressure” on the NHS.

The intervention came as Prime Minister David Cameron mingled with stars including The Wire actor Dominic West as leading showbiz figures gave their backing to the UK remaining in the European Union.

Hollywood actors including Benedict Cumberbatch, Chiwetel Ejiofor and Keira Knightley are among the big names who have backed the Remain cause.

The Cabinet Minister said that between 172,000-428,000 migrants a year would be arriving in the UK until 2030, meaning A&E attendances would spiral by between 6.3- 12.8 million annually, increasing emergency NHS demand by between 28 -57 per cent.