Parents of four and five-year-olds in Brent will found out today which primary school their children will be attended from September.

However, a government minister is warning that thousands of parents in England will be ‘disappointed’ when their children are rejected for their first choice school.

Priti Patel said it was “deeply regrettable” that families will discover on National Offer Day (today) that they are affected by a shortage in primary school places.

The employment minister, a Brexit supporter, blamed uncontrolled migration for putting “unsustainable pressure” on public services and warned the problem would only get worse as more countries became members of the European Union.

Ms Patel said: “The shortage of primary school places is yet another example of how uncontrolled migration is putting unsustainable pressures on our public services. Education is one of the most important things that Government delivers, and it’s deeply regrettable that so many families with young children are set to be disappointed today.”

Unions and town hall leaders warned Government reforms that mean all schools will convert to academies are set to fuel the shortage in school places.

Councils will not have the power to force schools to expand in the future, even where there is demand and capacity, the Local Government Association (LGA) said.

It warned that an additional 336,000 primary school places would be needed by 2024.

Roy Perry, chairman of the LGA’s children and young people board, said: “Most academies will be keen to work with their local authorities, but in the minority of situations where this isn’t the case, appropriate powers are vital to ensure all children get a suitable place.”

The Association of Teachers and Lecturers (ATL) said it was “worried” about the impact of the reforms.

Nansi Ellis, assistant general secretary, said: “We are already hearing that 90 primary schools have a catchment of only 330 yards from the school gate, and the number is likely to rise as the school population increases.”

Lucy Powell, shadow education secretary, said: “Ministers have already tied the hands of local areas to adequately plan for school places. The Tories’ new forced academisation policy will make the school places system implode, as councils lose completely the levers they have to ensure there are enough school places for children.”

According to the Department for Education the government spent £5billion creating places between 2011 and 2015 and 95.9 per cent of parents received an offer at one of their top three preferred primary schools last year.

“Despite rising pupil numbers, at primary, the number of pupils in excess of their school’s capacity has fallen by a quarter since 2010, and average class sizes have seen little change,” a spokesman said.

“Of course there is more to do - that’s why this Government has already committed to invest a further £7 billion to support councils in delivering school places, which along with our investment in 500 new free schools we expect to deliver 600,000 new places by 2021.

“It is simply not true to suggest councils cannot commission new schools - where councils identify that a new school is needed in their area they are required to run a competition to identify strong providers for a new free school.”