Something is badly wrong at the heart of one of Britain’s most important ministries. How did it become so broken?

For the thousands of people who end up on the wrong side of the Home Office each year, there is often a sudden moment of disbelief. This can’t be happening, people tell themselves. They can’t do this, can they?

For Ruhena Miah, a sales assistant born and raised in the West Midlands, this moment came when she received a letter saying that if she wanted to marry the man she loved, she would have to move to Bangladesh. For Tayjay Thompson, a young man convicted of a drugs offence when he was 17, it was when he was told he would be deported to Jamaica, a country he’d left as a toddler. For Monique Hawkins, a Dutch software engineer, it was when her application for a residency permit was rejected, despite the fact she had lived in the UK for 24 years. For Omar, a refugee from Afghanistan (who asked me not to use his real name), it was when he stepped off the plane at Heathrow and discovered that he was being taken to a building that looked to him very much like a prison.