It is just after seven o'clock in the evening, and the team at the monitoring centre are watching their computer screens. They are waiting for the electronic signal that will tell them that an offender has broken his curfew.
A phone rings, and the man on the other end of the line says breathlessly that he got a stitch running home, and that's why he's late. His failure to meet the conditions of his curfew has been revealed by the electronic tag strapped to his ankle.
A monitoring unit in his home, connected to a telephone line, has confirmed that he was not home on time. Now he has to explain why, or face the possibility of going back to court or prison. This is control centre is run by Premier Monitoring Services. It has the contract from the Home Office to operate the tagging system in London, Eastern England, the Midlands and Wales.
'The dog ate my tag...'
The staff hear some original excuses. Like the man who said he was out walking his dog when it became ill and he had to take it to the vet. Tonight, an offender who has arrived home just after his 7pm curfew tells the operator that he was stuck in traffic, coming home from work.
"I understand why you are late, but Home Office rules are very strict," the operator tells him. "I have to treat it as a violation of your curfew, and the time will be added to your record. You might receive a first warning for this, which means you are OK on this occasion. But you really need to try and keep to your curfew," she explains.
The need for offenders to watch the clock is seen as one of the benefits of the tagging system.
"It's something that actually instils a certain amount of discipline and responsibility," says assistant director Andy Homer. "We are very strict. We have to adhere to Home Office guidelines. Any breach of the order is either taken back to the court or the sentencing unit."
Norfolk was one of the areas where the use of electronic tagging was first tried in 1995. Initially, some in the criminal justice system were sceptical about its chances of success. But six years on, many have been won round.
Judge gives thumbs up
In the Crown Court, Judge David Mellor says he regards curfew orders as a valuable addition to his sentencing powers. "Correctly targeted, I think it is an excellent option. It isn't a soft option. I am sure there are those who come into court expecting immediate imprisonment who feel an immediate sense of joy and relief.
"But as the weeks turn into months, and they find that they are in effect imprisoned in their home, and all their normal pleasures and leisure is taken out of their life, I think they find it burdensome," he says.
Among those who initially expressed strong reservations about tagging were probation officers, who viewed it as purely punitive. Norfolk's assistant chief probation officer, Martin Graham, says his staff feel more comfortable now about the use of curfews as an alternative to prison.
"I think we've got lots of evidence now of offenders who say to us that the curfew has actually put some structure into their lives. That has then enabled them to work on some of their other problems, in conjunction with their probation officer," he says. "I've had probation officers say to me that they've been able to work quite successfully with offenders who they wouldn't have had a chance with, and the curfew has assisted them with that."
The restriction of an offender's liberty is not simply a punishment. It is seen as an opportunity to do something about their behaviour, and a curfew order is often combined with probation and community service orders.
"The whole essence of a curfew order is to try and interrupt a pattern of offending," says Julia Sharp, of Youth Justice. "So with a young person who was going out at night and perhaps stealing cars, we would be looking at a curfew overnight. It shouldn't be a stand alone sentence; it should be part of a package of intervention, addressing that young person's needs. We need to work with parents as well. You want them to see it as a way of reinforcing boundaries that perhaps they've had difficulties for years in reinforcing themselves."
Police 'agreeably surprised'
Police in Norwich were among those who were initially suspicious of tagging as an alternative form of punishment. DCI Bill Goreham says they are now "agreeably surprised" at the way it is working, although there is still concern that those placed on curfew are carefully selected.
"We have to look at the profile of the offender," he says. "Obviously, with someone who is a persistent violent offender, you have to weigh up the short-term risk to the public with the long-term benefits of trying to rehabilitate that offender.
"If we take an example of someone who has committed a drink-driving offence, at the moment they are subjected to a heavy fine, and they are disqualified from driving. Now some may say that's a big enough sanction. But if you were to add to that a curfew order, so that they have to be at home for so many nights, for so many months, then I think that reinforces the issue that as a society we are not going to tolerate drink-driving," he says.
Testing the boundaries
Another possible target for tagging are youngsters who get into trouble because their parents have difficulty in keeping them off the streets at night.
Julia Sharp of Youth Justice sees electronic tagging as a useful way of enforcing curfews for juvenile offenders. "A young person will often test it out. For instance, if they are curfewed at seven o'clock, they might come back at two minutes past seven. When they realise the system works, it gives them boundaries.
"Often with their parents, they'll push it and say they're sorry, their watch has stopped. But they can't argue with an electronic system, and it takes that responsibility away from parents, which is often a cause of friction within a home."
Judge Mellor sees other benefits from tagging some offenders, rather than sending them to prison. "The sort of offender one has in mind is the tax-paying citizen who has behaved in a way that would normally be met with a short term of imprisonment," he says.
"Instead of taking someone out of the community, so that he loses his job and the taxpayer has to support his family, and indeed support him in prison, it can be much more productive to lock him up at home."