More on the green/yellow uniform:
"Prisoners who have made active attempts to escape from custody are placed on the holding prison's Escape List. These prisoners (sometimes referred to as "E men" or "E List men") are required to wear distinctive, brightly coloured clothing when being moved both inside and outside of the prison and are handcuffed. In addition they are required to change cells frequently and to have their clothes and some of their personal property removed from their cell before being locked in for the night."
Source:
Prisoner security categories in the United Kingdom - Wikipedia
So he tried to escape since last week? That's a fair inference I would think. Jesus.