It doesn’t look anything special. From the outside it is just another house, with nothing to suggest it is the hub of a concerted effort to change the nation’s schools. Even the piles of papers and files scattered around its rooms give little indication of the influence wielded from within its walls.

But this unassuming bungalow on a quiet residential street on the outskirts of York is home to the Campaign for Real Education (CRE), one of the most high-profile lobby groups in education.

Though far from being the only group aiming to shape education from the outside, the CRE is one of the most vociferous, and has an impact out of all proportion to its resources. But Nick Seaton, its chairman, freely admits his qualifications are limited.

“All I know about education is from a short course at York University and from books,” says Mr Seaton, a retired wholesale car dealer. But that hasn’t stopped him helping to create a climate where school performance tables are now generally accepted and concern over standards is widespread.

Other areas of public policy, such as health, have their own pressure groups, but rarely are they as numerous as in education.

“The thing about education is that the evidence is always relatively weak in relation to the narrative,” says Alan Smithers, director of the Centre for Education and Employment Research at Buckingham University. This creates a climate where lobby groups can thrive, he says. Some, such as the Anti Academies Alliance, focus on a single issue. Others, such as the Campaign for State Education (Case), have a broader range.

Mr Seaton’s introduction to campaigning came when he joined protests against the decision to close York’s grammar schools. Finding common cause with other parents’ groups, he set up CRE 22 years ago, with the twin principles of “higher standards and more parental choice”.

For Mr Seaton, higher standards require some level of competition. “If all schools are exactly the same they sink to the lowest common denominator,” he says. And while he does not advocate unfettered parental choice, he argues for a greater role for parents in their child’s education, adding: “We’re generally in favour of the consumers rather than the producers.”

His approach certainly seems to strike a chord. The CRE’s website receives about 12,000 hits a month, and the group was cited 166 times in the national press in the past 12 months, many times more than most other lobby groups, and comparable to some of the leading think tanks, such as the left-wing Fabian Society with 154 mentions (see table).

Although a crude measure, ignoring whether the mentions were positive or any radio or television appearances, it does give an indication of the campaign’s reach. Recent weeks have seen Mr Seaton appear in the press on issues ranging from Ed Balls taking a holiday when A-level results were published, to the Government enlisting “foul-mouthed rap artists” to promote music in schools. “We’re lucky that the media has been very friendly to us, and on most occasions they come to us for an opinion,” Mr Seaton says.

In the beginning, he ran the group from his son’s bedroom. Now, the entire house has been turned into an office, with papers and books everywhere, and his son’s bedroom is now filled with filing cabinets.

He describes himself as a traditionalist, and is concerned about schools teaching on social or moral issues. “It is using schools to change attitudes and values, which seems to us to be wrong,” he says. He is opposed to “value-free” sex education that just preaches to children, although in general he supports letting people make up their own minds. The campaign’s work is funded by donations from its 2,000-3,000 members, and is directed by a 12-strong committee, although Mr Seaton is its voice. “I try to take the view of the grassroots parents and we think the majority agree with us,” he says.

The campaign also lobbies local authorities or schools on behalf of individual parents, on issues such as admissions or the content of lessons. Its impact is perhaps more in helping shift the tone of the education debate than in achieving specific goals. Mr Seaton says he is gratified to see his concerns over school standards, first raised in the late 1980s, are now shared by many university admissions tutors and employers, and that school performance tables are widely accepted in England. “Parents find them useful,” he says.

After more than 20 years campaigning, he has lost none of his belief in the need to continue. “You are building a future and it just seems important that young people get a decent education,” he says.

While Mr Seaton became a campaigner to defend selective education, abolishing the remaining grammar schools is a principal plank driving the Campaign for State Education (Case), formerly the Campaign for the Advancement of State Education.

“We believe that public education is a moral good that ought to be supported by society,” says Michael Pyke, a member of Case’s national executive. “We believe selection should be abolished, including covert selection where schools are notionally accessible to all but in fact they’re not.”

Case stands at the opposite end of the spectrum to CRE. It’s against comparing schools; against the testing regime; sceptical about choice. It is fair to say the tide of education policy has been flowing away from Case for at least 30 years. Perhaps for this reason, it receives far fewer mentions in the press than the CRE. But it also lobbies politicians directly. Mr Pyke cites recent meetings with David Laws, Liberal Democrat education spokesman, and Barry Sheerman, chairman of the House of Commons select committee for children, schools and families.

An encounter last summer with Ed Balls was less successful. After being put off several times, Case was finally granted half an hour with the Schools Secretary, only for Mr Balls to arrive 10 minutes late, address the group on the misunderstanding they were Comprehensive Future, a related but separate organisation, and then leave 10 minutes early. “It was a very bad meeting,” Mr Pyke recalls.

Despite the apparent lack of success, or because of it, Case draws a majority of its members - numbering “in the hundreds” - from education. Mr Pyke, a former deputy head, is realistic about what they hope to achieve.

“Like any pressure group, we have to recognise that a lot of what we’re doing is simply keeping the flame burning, in circumstances where our views are not in line with conventional wisdom,” he says. He does see grounds for optimism in the Government’s waning enthusiasm for giving more autonomy to academies. “We’re getting our voice heard a lot more than we were three or four years ago,” he says. “I don’t know about the tide turning, although it certainly isn’t rising any more.”

Comprehensive Future is a spin-off from Case. Originally aimed at Labour Party members, though now open to all, it was launched in 2003 to concentrate on one issue: admissions policies. It opposes selection and claimed some success in tightening up a previous schools admissions code, requiring schools to act in accordance with the code, rather than just with regard to it.

But Margaret Tulloch, secretary of Comprehensive Future and former secretary of Case, recognises this is just tinkering. The prize is ending selection at 11, and while none of the main political parties wants to extend selection, none wants to change the status quo. “No one has the political courage to end selection,” Mrs Tulloch says.

Anti-selection campaigners had pinned their faith on the election of a Labour government in 1997, but the subsequent insistence that decisions to scrap grammar schools should be taken locally - and the vote to retain them in the only ballot held so far, in Ripon in 2000 - somewhat took the wind out of their sails.

It is hard to detect any confidence that their aims will be achieved any time soon, particularly if the Conservatives win the next general election, but Comprehensive Future is undaunted, at least for now. “We have to keep on making the argument because it is a sound one, but I do feel there is a limit to how many times you can bang your head against a brick wall,” Mrs Tulloch says.

But the group does have impressive contacts, boasting former Labour leader Lord (Neil) Kinnock and former Labour education secretary Baroness (Shirley) Williams among its patrons. Fiona Millar, partner of former Downing Street spin doctor Alastair Campbell, is the group’s chair. It has also held meetings with all four secretaries of state since it was founded, all of whom have been sympathetic, Mrs Tulloch says. “They all wanted to end selection, but without anybody noticing.”

Comprehensive Future has about 800 supporters, relying on them, plus donations from teaching unions, for its financial future. But when Margaret Morrissey founded her own group, financial independence was a key motive. She had been involved with the National Confederation of Parent Teacher Associations (NCPTA) for about 20 years, forming Parents Outloud last year.

Having no membership fees, Parents Outloud is answerable to her alone. “If you’re not taking any money then you’re not toeing the line,” she says. Parents Outloud was originally meant to give support to parents over education-related issues, but has developed into a lobby group. Her own qualifications are 30 years working with parents’ groups, and “common sense”, she says.

Perhaps as a result, she is regularly cited in the media, with 90 appearances in the national press in the past 12 months. She runs polls on her website, giving weight to her views, although she doesn’t claim to be a parents’ representative. “I’m not saying, ‘Parents think this’, I say, ‘This is my opinion’,” she says.

She first became a school governor after campaigning to stop a zebra crossing being installed on a blind corner outside her son’s nursery. Her children are now grown up, but she has remained involved in schools through looking after her grandchildren.

“As long as I’m actively involved in education I’ll carry on. When I’m not, it will be time to pass on to someone else,” she says.

She says she has good relationships with teaching unions and regular contact with ministers. It hasn’t always been smooth: she was called a “Neanderthal” by the Tory education secretary John Patten, but she has a particular regard for one of his predecessors, John McGregor, who served from 1989-90.

In her NCPTA days she was a vocal opponent of Sats, and was heartened when the key stage 3 exams were scrapped last year. “When you lobby, things don’t happen suddenly,” she says. “Often politicians leave it for a bit and then you see a result.” But how? Make them think it was their idea in the first place.