Forty British officials living in America face being thrown out of the country unless they spend thousands of pounds to become permanent US residents, the Telegraph can reveal.

The employees at Britain’s Washington embassy and consulates across America have been caught up in a crackdown on diplomatic visas being pursued by the US government.

Some of those affected have been working for the UK government for decades and have resorted to lobbying US senators directly in an attempt to remain in the country.

The uncertainty has placed immense strain on those affected, with some forced to leave their jobs and others employing outside lawyers to fight their case.

Questions have been raised about whether the UK Government has done enough to protect those involved.

UK sources insisted they were helping those affected but a US State Department official said Britain had made no request for the policy to be changed or dropped.

Stuart Baird, 49, a senior UK trade official who has worked at British Embassy in Washington since 1997, said: "I wake up more or less every single night at 2.30am, my head spinning.

"It will have a massive impact on our future," he said, speaking to the Telegraph in a personal capacity. "I’m effectively going to be unemployed and homeless. It is playing havoc with my mind."