Thorn Cross opened in December 1985 as an open youth custody centre on a former Royal Naval air station site that had been converted into an open prison for adults after the war. It operated regimes for young adults aged 18–21 and adults aged 21–25, but this upper age limit was removed in 2013.
Accommodation
- Units 1-5: each unit has 60 single rooms.
- Unit 6: 6 double rooms An additional four rooms can be used if a prisoner needs to be held securely before being transferred back to closed conditions.
- Unit 7: 33 double rooms
- Unit 8: 44 individual self-contained temporary living units to accommodate prisoners working outside the prison