Why did they use military barracks to house asylum seekers and why has it been deemed illegal?

The Home Office began housing asylum seekers in disused army barracks around September last year and in that time their use has been a regular feature in the news. The Penally Camp in Tenby, West Wales, which was used for this purpose, was closed in March following an inspection that found it totally unsuitable and unsafe. Napier Barracks, an even larger site housing asylum seekers in Kent, remains open and is thought to house a population of around 250 individuals.