The Department for Education (DfE) has been ordered to reveal how much it paid new academy sponsors to takeover failing schools, after a 12-month legal battle concluded in favour of transparency campaigners.

Department officials originally refused to reveal the cost of rebrokering 23 academies, from September 2013 to October 2014, because it said the information was “commercially sensitive”.

The costs were requested under freedom of information laws by campaigner Janet Downs, from the Local Schools Network.

She appealed the refusal but an independent reviewer at Information Commissioner’s Office (ICO) said the DfE was entitled to withhold the amounts.

But Ms Downs appealed the decision through the courts and last week it was overturned by a first-tier tribunal, with judge David Farrer QC shooting down the Department’s arguments.

The DfE had said releasing the information would put off future sponsors if they learned that other trusts had been given more cash to help with takeovers.

They also said unexplained variations in grants given to different sponsors could encourage them to “drive hard bargains” rather than concentrate on the “philanthropic objectives of the scheme”.

But the judge said this attributes to potential sponsors a “bewildering blend of naivety and financial opportunism”.

The tribunal also said any sponsor that was “too obtuse and too self-interested” to accept the need for differential funding may not be a “suitable replacement nor indeed fit for sponsorship at all”.

Mr Farrer QC also criticised the advice given to children’s minister Sam Gyimah by civil servants encouraging him to reject the information request.

“The evidence supporting that opinion was tenuous, to say the least, and the [minister] took no account of the possible weaknesses in the argument submitted, because they were never drawn to the minister’s attention.”

The DfE has until January 30th to release the data.

A DfE spokesperson said: “We will carefully consider the ICO’s decision and respond in due course.”