The demonstrators, organised by the Campaign Against Vouchers in Education (CAVE) will start at Battersea Park in south London, and will go through Kensington and Chelsea, another phase one borough, to a rally with speakers from parent groups, union officers and local authority representatives.

Opposition to the scheme began slowly, but is now rapidly gaining momentum.

Parents and councillors in Solihull, which provides a high level of nursery provision for three and four-year-olds, believe they could lose out on the scheme, and have organised lobbies and marches.

In Norfolk, one of the first phase LEAs, members of the Primary and Special Headteachers Consultative Group (PASH) claim the majority of the county’s 350 primary headteachers oppose vouchers.

The increased competition spurred by vouchers has also soured their relationships with playgroups in the battle for cash and four-year-olds, they say.

The county is offering what it calls “financial encouragement” to admit primary pupils part-time as early as possible. The National Association of Headteachers has calculated that schools’ budgets will increase by 10 per cent this year if they take all four-year-olds into their reception classes this September, instead of admitting summer-born children part-time in January, or as rising fives. If heads continue to take them only as rising fives, they will lose 17 per cent of their budgets. However, if they take the children the term before they are rising five, they lose 7.5 per cent.

Helen Banks, head of Clover Hill first school in Norwich, will be taking all children in September in order not to lose money. Her school will therefore gain Pounds 5,000 this year.

The heads believe many such children would be better off in a nursery than in a reception class. Tom Bellis, of East Harling primary school in Norwich, is under pressure to set up a new nursery by September and is expected to recruit for a nursery teacher from a county pool of newly-qualified teachers.

“I am gaining from bribe money, so I cannot not co-operate,” he said.

Barry Collins, a chair of governors at a primary school in Mixenden, Halifax, said protest was beginning to grow in Calderdale, and parents were putting pressure on Donald Thompson, the area’s Conservative MP, to oppose the bill or support a motion allowing LEAs to opt out.

He said: “We have a similar situation here to the one in Solihull, with more than 70 per cent of three and four-year-olds in nurseries or reception classes. The scheme has no advantages at all for us. All parties on the council oppose it and protest groups are being formed in every primary school.”

Liz Paver, head of Intake first school in Doncaster, said: “There are fears in this part of the country with high nursery provision that redundancies may occur because there will be no funding for three-year-olds.”

CAVE, the London-based anti-vouchers group, was set up after a National Union of Teachers-organised conference on nursery education. The union, together with Unison, the public employees’ union, has helped to fund CAVE.

Sarah Buckland, one of the founders, said: “We’re just ordinary parents who want to fight this scheme.”

The group Barnet Parents will be among others aiming to deliver a petition to 10 Downing Street.