In a department that has seen six secretaries of state in the past seven and a half years, Jim Knight stands out as a rare beacon of stability.

In fact, he informs The TES that he has only a few months to go before he becomes this Government’s longest-serving minister of state for schools.

“Estelle (Morris) still holds the record,” he said. “I think she did 33 months, and I must be on something like 29 - if I make it to Easter ...”

But records are all very well. The 43-year-old, who has successfully straddled the Blair and Brown governments, is now facing his biggest challenge yet as schools minister.

Last month’s mini-reshuffle handed him a huge new responsibility - taking over academies from Lord Adonis, the former junior schools minister who has done more than all others put together to promote the controversial policy.

Mr Knight must now face wary academy sponsors, upset and unnerved by the sudden removal of their champion, and persuade them to commit further as the Government seeks to meet its pledge to open 400 of the state-funded independent schools.

It is a programme which he admits he has not always been convinced by. Asked if he had ever had reservations about the Government’s flagship schools programme, Mr Knight said: “There have been times before I came into the department when I read the reporting rather than visited academies, and was to be persuaded.”

But today, having witnessed the reality, he says he is a true believer. “Since I started visiting (academies) and seeing how they worked for children from communities where successive generations have been let down by schools, I am an enthusiastic proponent of them and advocate for them,” he said.

That is the official line. But others who have worked closely with him on policy sense that he may retain some scepticism, or at least caution, about a policy in which success is far from proven.

One senior teaching union member of the Government’s social partnership said: “I don’t think he believes that if you sprinkle fairy dust on a school and call it an academy, then all its problems are over. I think he believes the programme needs stronger quality assurance.”

Mr Knight certainly mounts a robust defence for the changes to the academies programme brought in under Ed Balls, the Schools Secretary, which have led enthusiasts to claim that the policy has been watered down.

On moving the emphasis away from commercial sponsors by letting “educational” sponsors such as universities and schools off making any financial contribution, he says: “Allowing educational institutions to risk their brand rather than risk their money has made it easier for some of those to come in.

“It is still a big decision for a high-performing school or a high-performing FE college or university to get involved because they are putting their reputation on the line, and that is worth a lot. But there will be private sector sponsors who have the same motivation and will continue to come forward. I am not ideological about it.”

But will they continue to come forward in the same numbers? One private sector sponsor approached by The TES said the personal relationship Lord Adonis had built with sponsors had been crucial in encouraging them to get involved.

Without it, he was unsure about making any further commitments.

“Being an academy sponsor involves battles and heartache, tough negotiations and time,” the sponsor said. “You want to know that the people you are dealing with will stand by you when criticisms come.”

The impression his predecessor made on sponsors is not lost on Mr Knight. “I completely understand that Andrew’s record in personally championing - sometimes, it appeared, personally brokering - the academies, and being intimately involved in every single project, would mean that there would be huge affection towards him from people in the academies movement.”

So, will he have time for the same degree of personal involvement? Mr Knight admits that despite being relieved of his curriculum responsibilities, he may not.

“There is inevitably an issue as we are moving from 100 academies to 200, and then 400, as to whether a minister can have the same attention to detail for every single project,” he said. “There will be some change that is a reflection of scale rather than commitment.”

But he is keen to stress that in all other respects it will be business as usual. “We should all be hugely grateful for Andrew’s contribution, which has been immense, so of course I can understand that there would be nervousness about moving on to realise his other dreams in the cabs of trains.” he said.

“But I hope that they know that in passing on the responsibilities to me, they have someone who they can do business with, who shares Andrew’s impatience and passions.”

The crack about Lord Adonis’s trainspotting persuasions - his rail enthusiasm apparently helped to make his new transport brief a particularly attractive one - is typical of Mr Knight’s relaxed, jokey style.

Occasionally, in more formal settings such as select committee hearings, it has seemed to some a little too jokey.

But the former theatre producer’s affability and reputation as a grafter have won him many friends and a lot of respect in education.

Mr Knight’s extensive blogging and use of social networking websites have probably also helped. The father-of-two has 883 Facebook “friends”, who have been able to keep close track of everything from the nervy waits for a call from Number 10 during a reshuffle, to the frank admissions of procrastination on the internet.

But the minister’s popularity has not always extended to teachers, as Mick Brookes, general secretary of the National Association of Head Teachers, acknowledges. “I think people that don’t know Jim might have trouble separating the personality from the policy,” he said.

“They would judge him on policies and some of those are particularly unpopular among my members, such as the key stage 2 tests and the general low-trust climate. But I like the bloke. For a politician he is pretty straight.”

Even senior sources from the National Union of Teachers - the teachers’ union left out in the cold by the Government - describe him as “probably one of the best schools ministers we have had”.

Mr Knight says he is proud of many things in his current job - right from his first decision to introduce nutritional standards into school meals to his most recent one to introduce statutory PSHE and sex education.

“But the thing that I think will be the most historic is the legislation to raise the (compulsory education and training) participation age to 18,” he said.

And his biggest mistake?

“What mistakes?” he laughs, before nominating his gaffe at the Association of Teachers and Lecturers’ conference last year, where he “allowed a comment that I made about class sizes to be misinterpreted so that some people believed that I thought a class size of 70 was OK, which certainly isn’t the case”.

Others might nominate his appearance on the BBC’s Today programme to discuss the National Challenge, when he used the word “failure” while talking about secondaries involved in the school improvement scheme. His boss, Ed Balls, had gone out of his way not to use the F word.

“The National Challenge 638 was certainly not a list of failing schools, and if anyone interpreted anything that I or anyone else said (as saying that), then obviously I would regret that,” he said.

But he still blames the media rather than ministers’ get-tough rhetoric for creating that impression. “If I started taking responsibility for what news editors decide to put in headlines, I would be a very unhappy man,” he said.

Whatever the truth, there is no getting away from the huge amount of bad feeling the policy has created among schools. Indeed, that may be why ministers are now considering a very different approach to raising attainment in primary schools.

Mr Knight reveals that dropping the idea of a results benchmark that schools must reach is a possibility. Alternatives, such as report cards and Ofsted verdicts - which give a more rounded verdict on school performance, as opposed to raw results - are being considered.

But ultimately it is the opinions of his electorate in Dorset South, rather than just those of teachers and heads, that will have the most bearing on his future career.

The constituency is one of the most marginal in the UK, where Mr Knight has a majority of just 1,812.

So, will he still be an MP after the next general election?

“No one has ever predicted that I would ever win my seat at any election,” he said. “There is everything to play for.”

JIM KNIGHT: THE CV

Born: March 6, 1965

Educated: Cambridge University

Family: Married with two children

Career before politics: Managed arts venues, worked for a travelling theatre company, managed a publishing company based in the West Country for 10 years

Political career

June 2001: Elected MP for Dorset South,

2001-2003: Member of Defence Select Committee

2004-5: Parliamentary Private Secretary to Rosie Winterton, Department of Health

2005-2006: Parliamentary Private Secretary to ministerial team, Department of Health; Minister for Rural Affairs, Landscape and Biodiversity at Defra

May 2006: Minister of State for Sschools, October 2008 Takes on responsibility for academies.