Parent power: Sara Payne on being an ordinary mother in Whitehall

She was an ordinary mother, but her child's shocking death gave her a national platform – and the power to make a Prime Minister sit up, listen and respond to what she was saying.

It's a description that applies to Sara Payne every bit as much as it applies to the woman who is this week centre-stage on the nation's news bulletins, Jacqui Janes – but while Janes, whose son Jamie died in Afghanistan last month, has only just embarked on the role of bereaved mother-turned-campaigner , Payne is an old hand. She has spent the last nine years living, sleeping and breathing a legacy she'd have done anything to have avoided: that of trying to make the world a safer place so that other parents don't lose their children as she lost her child.

In Payne's case it was a daughter, Sarah, who died, aged eight, at the hands of a man who snatched her from a field where she was playing on a summer's day in 2000. Payne had to wait 17 agonising days before her daughter's body was discovered; then there was another wait before the killer, who turned out to be a convicted paedophile named Roy Whiting, was caught and tried. As the truth about Sarah's death emerged, her mother realised – just as this week Jacqui Janes believes she has realised – that if things had been done differently, her child might not have died. While Janes argues that the provision of extra helicopters in Afghanistan might have saved her son, Payne argues that the existence of a sex offenders' register might have saved her daughter – she has always said that if she'd known about Whiting's history, and that he was living in the area, she'd never have let Sarah play in the field that day.

So where, more than nine years on, has her tireless campaigning got Payne? Today the woman who once sat where Janes sits – looking, like her, gaunt and tearful under the TV lights – is rounder-faced and far from tears. What hasn't changed, though, is the dignity and resolve she first displayed all those years ago in the early days after Sarah disappeared. "When you bury your child it's not natural in any shape or form," Janes told reporters a few days ago – and there's clearly a drive born of that terrible moment, and the realisation that things could and should have been different, that doesn't disappear or dissipate. So this week Payne was every bit as determined as she was back in 2000: and though her fight for 'Sarah's Law' – a measure which would give parents information about the whereabouts of paedophiles – has already led to 15 new pieces of legislation taking her some way towards her goal, she is still fighting. "There's a pilot project going on at the moment," she says (it gives parents the right to ask the police for information on anyone who has unsupervised, direct access to their child). "And the evaluation will be carried out in January, so the next step is that we find out whether that will go nationwide."

One thing Payne couldn't possibly have foreseen is that, almost a decade on, she'd be a government insider – since January she's been working at the Ministry of Justice as 'Victims' Champion'. When we meet at the Ministry, in central London, I'm immediately struck by how incongruous all this is: Payne, who until her life changed that summer's day in 2000 worked as a barmaid in a Surrey tavern, looks entirely out of place surrounded by civil servants – and in the nicest possible way. She's too straight-talking and down-to-earth to spend long playing politics – which is probably why the Ministry of Justice has assigned us a minder who seems to have had it drummed into him that he must on no account leave Payne alone with a journalist, even for a second. When the photographer arrives downstairs it's almost painful to see him trying to work out what to do – Payne shoos him out of the room telling him she'll be all right, but within seconds he's back, having despatched another lackey to collect the photographer. As this week's events have underlined, like real life imitating the fiction of TV's dark political satire The Thick of It, there's no knowing what can happen when an ordinary person who tells it like it is gets the chance to do just that – and no-one at Whitehall is taking any chances.

Some critics have said that the decision to pull Payne on board was inspired: from being a potential troublemaker for politicians, they say, she's become part of the team. When her report into the criminal justice system from the viewpoint of the victim was published last week, some lobbying groups – Victim Support among them – hinted heavily that it said nothing new, that it failed to grasp the bigger picture, and that it was likely to lead to few real changes. In other words, Payne was an amateur stumbling through territory better left to professionals like them. Payne, though, is having none of it. "If people are saying nothing is going to change, I find that incredibly defeatist," she says. "Lots of things have changed already, like all these bits of legislation about paedophiles. I genuinely believe this report will spark change – the Government is considering it at the moment, and will respond at the beginning of next year."

There may be a touch of naivety about her here – one commentator last week said her report was exactly the sort of document that looks ripe to disappear straight into the ether – but there again, there's a strength in that kind of naivety. Also, while it's true that Payne may at times be grappling with issues that are newer to her than to some of those who work in the victim support field, it's also clear that her refusal to play the usual political game often works to her advantage. Being a single-issue and utterly committed campaigner, motivated by a need to make something good come out of the senseless death of your own child, is a pretty powerful cocktail set against what often feels like the faceless cynicism of Whitehall.

Do the civil servants ever patronise her? "Absolutely not," she says. "When I started this job, as much as I may have been sceptical of them, they were sceptical of me. But people here have been fantastic – we're a team and I bring what I bring to the team just as each person who's part of it does." I'm sure that over the last nine years people have tried to patronise her, but I'm equally sure that Payne is telling the truth when she says she's never felt it – she's a tough cookie, and certainly no-one's patsy. "No, I don't feel I was used by the News of the World" (the paper backed her campaign and got a lot of mileage out of it). "It's been nine years now, and I don't think anyone could think I'd been used for that amount of time. I've never been pushed into doing anything I didn't want to do – in the early days it was me doing the pushing to get things done. If anyone was doing the using, it was me."

One thing she's keen to set straight is that many newspapers last week misreported one of the key issues of her report. She didn'tever say, she emphasises, that she felt offenders should get longer sentences; what she did say was that she felt that the criminal justice system should be able to say clearly – for the public as well as for victims – how much time in jail a convicted criminal would serve. "What I meant was, don't say life unless the person really IS going to spend their life in prison... and as we all know, that hardly ever happens. It's all about being honest, being clear. What people want to know is how long will actually be spent behind bars, and how long on probation."

If she could only change one thing, says Payne, it would be the way victims are treated when they find themselves, through no fault whatsoever of their own, caught up in the criminal justice system. "I want to see a system in which each victim is properly assessed, and his or her needs are met. Different people will need different things – some people might need help sorting out their locks, others will need years of trauma counselling. It depends on the crime, and it also depends on the individual."

The isolation and difficulties victims face when they find themselves in a courtroom – an environment entirely foreign to most of them, somewhere they've never been before and never expected to have to go, somewhere where there are strange people who wear wigs and speak a different, and often impenetrable, language – is something else she feels passionately must change. "People need better guidance through the system," she says. "There's the witness system which is helpful in some cases – but there again, it's staffed by volunteers. Victims deserve a properly-resourced professional support service."

Another big concern for Payne is those victims who never see anyone punished for what happened to them, because no-one is ever caught. "If that happens, there's no need for the police to keep up a relationship with you," she says. "They might update you on the case – but then again, they might leave you in the cold." What's needed, she stresses, is an overhaul of the system that takes proper account of the needs of victims, who at the moment are usually treated as no more than add-ons in criminal investigation rather than as individuals who have been through a traumatic event, and who need tailored and caring support. Just like Janes, who said this week that her son and her family "aren't just numbers, we're real people with feelings", Payne has a similar goal: she wants to hammer home to Whitehall bureaucrats and Westminster politicians that people who get caught up in events over which they have no control should not be doubly disadvantaged by being treated disrespectfully by decision-makers. And if the litmus test of any society is how it treats its most vulnerable, the work of women like these mothers is significant work indeed.

Payne is adamant that she has no criticism whatsoever to make of the way her own family was treated, either in the days, weeks and months after Sarah's disappearance and death, or during Whiting's trial. "We were treated very well," she says. "The police started searching for Sarah from the very first night, and they kept us properly informed throughout. The family liaison officers were helpful and inclusive, and we had trauma specialists to help the children" (her sons, Lee and Luke, were 13 and 11 when Sarah went missing; another daughter, Charlotte, was five). "But not everyone has the support we had, and that's what I'd like to see changed." When she was compiling her report, says Payne, she spoke to hundreds of victims who'd had nothing like the back-up she had – and some of them, like her and her family, had been through heartbreaking traumas.

Payne seems perfectly at ease talking about people as 'victims' but her very role seems to be another incongruity – while she's every inch the 'champion', she's about the least likely 'victim' you could ever expect to meet. And perhaps it's that slight bolshieness that's led to an aura of faint unpopularity around her – that and the fact that her News of the World campaign to track the movements of paedophiles played to the worst prejudices of the paper's most unenlightened readers, as well as representing, in the minds of many, an attack on civil liberties. But, even though it's nearly a decade since Sarah died, Payne still has bad days and even bad weeks when it's hard to cope with what she had to go through. "I have times when I can't and won't do anything because it's too close to the surface. But I get through because I've got the support to get through," she says, not missing an opportunity to bang the drum for her cause. "If I have nightmares, I know who to talk to; if I have flashbacks, I know who can help."

One legacy of losing Sarah the way she did has been a gripping fear that something similar will happen to one of her other children. Luke and Lee are now in their twenties, and Luke and his partner have a three-year-old, so the 40-year-old Payne is a grandmother; she also went on to have a fifth child, the now five-year-old Ellie, soon after she split up with her husband, Mike. But it's Charlotte, 15, who causes her the most headaches (as the mother of a 15-year-old myself, I can sympathise – I know how readily they go off the radar and you're left wondering not only when, but whether, you're ever going to see them again). But while for an ordinary mother like me it's a worry, for Payne it can quickly become a plunge back into her deepest nightmare. "My kids understand that. I know I can be paranoid," she says. "As a family we even joke about it. But the fact is that everyone understands why I need to know my daughter is OK – I've got all her friends' mobile numbers, as well as hers. I've even been known to go off searching for her when she's not told me where she is.

"But the bottom line is that my children are a lot more aware than other people's children about stranger danger and about the risks. And there will be issues for them with their own kids, and issues for them right through their lives, because of what happened to their sister."

Put bluntly, she says, there's no such thing as psychological recovery from what she's been through. "I don't think you can ever really recover and I don't think you can ever go back to who you were before. What it's about for me and people like me is learning to live with how your life is now – that's all you can do."

Although she wants to focus on the ways in which the criminal justice system fails the needs of victims, Payne is candid that seeing Whiting caught, and tried, was vitally important to her – so her own experience seems to underline that the system is right to put its biggest effort into what matters most, for victims as much as for the wider community. "I was there every day of the trial. Yes, it absolutely mattered to me to be there – it was important to me."

In the interview room she's cool and articulate: when we've finished, she's a bit flustered again about how to find her way around the labyrinth of the huge Ministry of Justice building. "How do I get back to our office?" she asks the minder, who's breathing a sigh of relief that it's all over. I ask for her mobile number so I can check anything I can't read in my notes, but it's clear I'd have more chance of getting Gordon Brown's number than hers – if I need her again, the route is through the minder. All the same, Payne is making waves – her post of victims' champion will be wound up in January to make way for the substantive post of victims' commissioner – and Payne isn't ruling out applying for that. For now, though, she can't wait to get back home to her family. When you've had to live through the unthinkable, you never take the people around you for granted again.