By Dominic Casciani
They call it the Boss. But you'd be forgiven for thinking that it's Old Sparky.
Segregation beckons for those who deny the Boss
The Body Orifice Security Scanner is indeed an electric chair-of-sorts.
But rather than being a backdoor attempt to reintroduce capital punishment, it's the new frontline in the battle against drugs and smuggling in prisons including HMP Woodhill in Milton Keynes.
So what does the Boss chair do? Well, swallow a mobile phone Sim card and see what happens when you sit down. It beeps. And that's enough for an inmate to be segregated until he reproduces the item from places best left unmentioned.
Mobile phones are a huge problem for prisons. They're small, light and increasingly difficult to detect given that they are mostly plastic.
Which is why the £6,500 Boss has been introduced to eight prisons and could soon appear in many more.
In essence, it's a highly sensitive metal detector which reduces the need for intimate and confrontational body cavity searches. Rubber gloves are being put away in favour of technology and a patient waiting game.
If the alarm beeps, then the chair has detected metal inside the prisoner. It's sensitive enough to detect the merest wave of a paperclip.
Prison officials say a bodily-concealed sim card, let alone a complete mobile, would produce the same result. If the inmate does not give up the item, then they go to the segregation unit until they do. If they try to flush the item down the cell toilet, the plumbing has been set up to allow officers to intercept the contraband before it hits the drain.
The chair however, can't detect drugs themselves and so sniffer dogs and body orifice searches are still necessary.
Only this week Woodhill identified a "plugged phone". A prisoner suspected of making "hooch" alcohol suddenly had the urge to visit the loo. The call of nature was not all it seemed: he had dashed off to tuck away a mobile in a body orifice.
But thanks to a Boss chair detection, that inmate was on segregation when the BBC visited the jail on Wednesday: the offending article had yet to reappear.
Traditional ways: One of Woodhill's drug dogs
One prisoner who produced a beep earlier this year, held out for four days in segregation before finally giving up the phone he had hidden away.
The prison service uncovered 3,500 mobile phones or sim cards across all jails in the year to September, according to official figures. Some 21 phones have been intercepted at Woodhill prison since April.
A recent report into Wandsworth Prison said there was an "apparently limitless" supply of phones in the jail which were pivotal to criminal enterprises. If someone has access to a phone, they can run drugs operations and intimidate witnesses.
Of course, there were drugs in prisons long before mobiles were invented. But the mobile has become a key instrument in the shipping of drugs onto wings. And if the substances cannot be stopped, then neither can offending.
The Wandsworth report called for signals to be blocked - but Prisons minister David Hanson says it's not so simple.
"I'm happy to look at that but there are jails like Woodhill which are surrounded by residential areas and businesses," he says. "It would be difficult to put these blocks in place."
And so he says he wants to see more Boss chairs in place from next year.
Just last week, a Woodhill prison officer was charged with allegedly supplying drugs to inmates.
Officials can't comment on the allegations because they are now before the courts. But Woodhill's governor Luke Serjeant talks frankly about the problems at his jail.
Its 790 inmates are a complex mixture of criminals dealt with in local courts and a small number of extremely serious offenders. There is also a special "close supervision centre" holding a handful of the most dangerous men in the country.
With about a third of prisoners on remand, the constant traffic to and from courts increases the likelihood that inmates will try to smuggle in mobiles and drugs.
Maximum security: But drugs still get in
"They use mobiles to arrange drugs coming in - they are key to internal drugs trade," says Mr Serjeant.
He says that he wants to turn around the lives of failing inmates. But like all governors, he needs to stop the drugs trade.
"Stopping drugs is not just about this being a closed prison - it's extremely important for the long-term prison population. We do not want a prisoner coming to us and then leaving with a drug problem because they have been sucked into it.
"If people come in here and think that this is their opportunity to put themselves straight [and get off drugs] then we have to provide that environment."
John, an inmate serving 12 months for theft, says during his years behind bars - including a decade for armed robbery - he has seen drugs increasingly become a key issue inside prisons.
"But there are more drugs in society," he says. "It's not just criminals using drugs. It's solicitors taking cocaine too. Everyone."
Was he aware of a lot of mobiles on the wings of Woodhill?
"No comment", he replied.