Drastically reduced immigration following Brexit would substantially raise the retirement age, with a sharp decrease in the numbers of working age people left to sustain the pensions of the elderly.

The state pension age is already expected to increase as a consequence of increased life expectancy and a surge in retirees among the baby boomer generation. But research from the Oxford Institute of Population Ageing indicates if current migration levels are not maintained, people will have to work for longer to meet the tax deficit.

Professor Sarah Harper, chair of the government’s foresight review on ageing societies, told The Guardian: “The message from Brexit is if you don’t want immigrants, you’re going to have to work longer. That’s how the sums work.

“Since the middle of the 20th century, the UK, like many other advanced economies, has employed migrant labour to reduce the ratio between older dependants and workers, which has arisen as child-bearing rates have fallen and people have lived longer.