The country’s most powerful union leader has accused the Government of short-termism and attacked the Prime Minister’s advisers for favouring educational policy gimmicks over the real business of raising standards in schools.

In an interview with The TES, Dave Prentis, general secretary of Unison, the biggest school support staff union, said it was working well with the Department for Education and Skills. But Downing Street had gone down a cul-de-sac about choice that was “not helpful to say the least”.

By encouraging the notion of a market in school places they were, he implied, benefiting some parents and schools at the expense of overall standards.

“For me you can only have real choice when capacity is sorted out, otherwise it is choice at somebody else’s expense,” he said. “Downing Street and the political advisers there have been pushing lines about more choice in schools when what they are really talking about is the ability of schools to choose their parents.”

He criticised Downing Street for finding a “new gimmick for the week” instead of concentrating on the improvements in standards that his members, who were at the sharp end, were seeking.

Policies to improve public services would take years to deliver but politicians wanted headlines the following week.

Asked if he thought Tony Blair, who he cheekily referred to as a Tory in a speech last year, should remain as a Labour leader, Mr Prentis said: “We have never sought regime change in London.” But smiling, he added: “It is really good for the party to have two leaders.”

The teaching profession is split among no fewer than six unions in England alone. But Unison, the country’s biggest, has successfully managed to combine the interests of everyone from school caretakers to town hall and police clerks, hospital porters and teaching assistants under a single umbrella since its formation in 1993.

With around 1.3 million members and an estimated pound;10m strike fund behind him, its leader has been described as one of the four most influential figures in Britain’s public services. Colleagues describe Mr Prentis as incredibly bright and affable but with a “very hard streak”.

“You would not want to make an enemy of him,” said one.

He said he did not seek to run the country but would not shy away from making the Government uncomfortable if that was what it took to represent his members’ views. Mr Prentis tempered his criticism by praising the Government for investing pound;60 billion in public services. But he repeated warnings that Unison could take strike action and pull out of the school workload agreement if it was not funded properly.

If the agreement, which began in September, was going to improve standards, support staff needed to be properly paid and trained; it was not “a no-cost option”.

He did not think the first year of the deal had been funded adequately. But getting results from any talks with the Government was always slow, “like drawing blood at times”. He was now lobbying for sufficient funding for the agreement in 20045 and over the next three-year comprehensive spending review.

If the money did not come through, Unison would have to review its commitment to the agreement. But he defended the principle behind the deal and condemned the National Union of Teachers’ position and reaction as “hysterical”.

Glancing out of his office window at the NUT’s Hamilton House headquarters, within spitting distance of Unison’s Mabledon Place office block, near King’s Cross, he said the teaching union’s publicity campaign against the agreement had been unhelpful, quite personal and had misrepresented other unions.

Assistants could teach whole classes and provide cover under the agreement, but only on an emergency or short-term basis, where they were supervised and properly trained. The irony was that 30 per cent of his support staff members had been doing so anyway before the agreement.

DAVE PRENTIS FACTFILE

* Born and brought up in Leeds.

* BA in history from London university and MA in industrial relations from Warwick university.

* Joined Nalgo’s education department in 1972, appointed assistant general secretary in 1983.

* In 1990 appointed Nalgo deputy general secretary, a position he retained in 1993 when the union merged with rivals NUPE and COHSE to form the country’s largest union, Unison.

* Elected general secretary 2000, described by one pundit as, “Mr Mainstream, an ideal replacement for Rodney Bickerstaffe, known by many as the Prime Minister’s friend.”

* Takes up post in 2001 after recovering from a stomach tumour, initially thought to be inoperable.

* By 2002 his “independence” had been reported as causing concern in senior government circles and he had been tagged as the elder statesmen of the new left-wing union “awkward squad”.

* Today colleagues claim a “politically astute” Prentis has placed Unison in exactly the right position - prepared to engage in social partnership with the Government, but not afraid to stick its neck out and criticise when necessary.