The non-UK born population of Britain has continued to surge after the Brexit vote, hitting a record high and approaching 10 million, with much of the growth down to open borders with Europe.

Jumping by 3 per cent in one year, the non-UK born population surged from 9.2 million in 2016 to 9.4 million in 2017, according to the latest Office of National Statistics (ONS) numbers released Thursday.

The non-British citizen population increased from 6.0 million to 6.2 million in the year, rising by up 4 per cent over the same period. The number of European Union-born people in the UK rose by 170,000 last year to 3.7 million.

According to think tank and pressure group Migration Watch, the increase from the EU alone is greater than the population of Harrogate.

Breaking the number down, the Romanian-born population of the UK grew by 80,000, to 390,000, suggesting migrants may be rushing to the UK before border controls are introduced after Brexit. Romanian migrants are now as numerous as the Irish-born population, traditionally a significant minority in Britain.

However, there has been a post-Brexit slow down in EU migrants applying to work. EU applications for National Insurance Numbers, which include short-term workers, are down by 120,000. Despite the fall, applications are still running at nearly half a million.

Commenting on the latest figures Alp Mehmet, Vice Chairman of Migration Watch UK, said: “There is still no sign of a net outflow of EU-born people as a result of Brexit. Indeed, they are still coming in significant numbers and contributing to a population increase which is simply unsustainable.”

Nicola White of the Migration Statistics Division at the Office for National Statistics said: “Non-UK born and non-British populations continued to increase in 2017, as more people continue to come to the UK to live than move to live abroad for a year or more.

“Poland-born residents and Polish nationals were the most common populations from outside the UK, with an estimated 1 million Polish nationals now living in the UK.

“However, the largest increases in population were seen from those born in Romania and those with Romanian nationality.”