A record number of people lost their lives in UK immigration detention centres in 2017. Eleven people died last year – one shortly after being released – which is more than double the number of deaths in 2016, and the highest figure since Britain began locking up migrants in 1970.

When the first detention centre was built 48 years ago, close to Heathrow Airport, prisoners could be counted in the dozens and were mainly those people who had been refused entry on arrival. According to the latest figures, just over 3,000 people are being detained at any one time, with roughly 30,000 individuals going through the system every year.