Inside the perimeter walls, away from the main body of the jail, and with another barrier of its own, is a small self-contained unit, a prison within a prison. In here a handful of the country's most dangerous prisoners - nearly half of them IRA terrorists - expect to live out their useful lives.
They are prisoners who pose the greatest security risk - men with a long history of violence, mostly facing sentences of 20 years or more and with little to lose by escaping or disrupting prison life.
It is from this special secure unit last week that six men did what was thought impossible. They escaped - albeit briefly.
But their armed breakout has highlighted attention not only on security at the unit and within Whitemoor prison, but on the apparently privileged lifestyle available to inmates in these units. Lobster takeaways, Reebok trainers and stonewashed jeans apparently feature on the prisoners' shopping lists, fulfilled by disgruntled staff who say they were not hired to run errands for inmates.
There is a small gymnasium, a television room, a hobbies workshop, kitchens, a visitors room and an exercise yard. Prisoners wear their own clothes, curtain and furnish their own cells, and after they are unlocked at 7.45am they are largely left to their own devices. They cook their own food and do their own laundry. They have largely unlimited access to telephones and visits.
To a Home Secretary who has been advocating 'austere regimes' and who is anxious to appear tough on law and order in the run-up to next month's Tory party conference, the revelations have appeared a major embarrassment. Both he and Derek Lewis, director general of the Prison Service, have been maintaining that no special privileges are granted to IRA prisoners. The truth is that terrorists get the same special privileges as other hardened criminals.
The reason for a softer approach to the hardened criminals is an attempt to balance tough security with humanity. Basically in such a closeted environment, where prisoners are volatile and tensions high, it is sensible to try to keep them reasonably content.
And few disagree that, despite the privileges, life in the unit is unpleasant. It is a tiny part of the prison, the exercise yard barely bigger than a netball court. The men are limited to the company of a very small number of fellow inmates and there is no prospect of change for years. As one prison officer said yesterday: 'It is still tough. These people see only a small piece of sky, day in, day out.'
In fact this row over exceptional privileges centres on only about 20 of the 50,000 prisoners in England and Wales. Whitemoor's special secure unit is only one of three in the prison network holding only a handful of people. The second is at Full Sutton, in York, and a third at Parkhurst on the Isle of Wight is being refurbished.
The units were an innovation of the Sixties and for the past 30 years they have been regarded as a success. Last weekend's was only the second escape from a unit; the last was in 1976.
The escape attempt now raises questions not only about whether the prison service has the balance between security and humanity correct - but also about the future of the units.
Stephen Shaw, director of the Prison Reform Trust, said: 'With the IRA prisoners being repatriated, there will not be many men in these very expensive units, especially as events last Friday raise doubts over the degree of security which is claimed for them.'
But yesterday Mr Lewis said there were no plans to shut the units, as there would always be a number of very high-risk inmates needing a high degree of security.
He said that the question of other privileges and sanctions was already under review throughout the prison system, although this would take time to implement.
However, takeaways and trainers may soon become a thing of the past. Mr Lewis said that he would urgently tackle the question of access to private funds which had allowed the prisoners their luxuries.