A quick glance at the glass cabinet is all you need to realise you are about to mix with Britain’s most dangerous teenagers.
Such a case in a school would be full of glittering sports trophies but in this forbidding Victorian jail it holds far more sinister mementos.
On display is an armoury of deadly weapons, made from seemingly harmless objects, found in cell searches.
A stark warning to the prison’s 185 wardens of the underlying violence that can surface at any time.
Among the vicious items are sharpened screwdrivers nicked from workshops and a blade, made by wrapping a severed tin can lid around a biro, perfect for what gang slang calls “shanking”.
“Take care in there, lads,” says a guard as we cross the no man’s land between the gatehouse and the main prison wings.
Aylesbury young offender institution holds 400 of Britain’s toughest young criminals – more than one in five are doing life for murder.
So, it is slightly unnerving to see 19-year-old gang killer Nathan holding a knife when I meet him. He is one of five lifers making chips in the sweltering staff mess kitchen.