An agreement has been reached to sell Norfolk's outdoor learning centre Holt Hall - but the identity of the buyer and how much they are paying is currently secret.

It is understood the mystery purchaser intends to use the building as a home, not for educational purposes - which has angered critics of Norfolk County Council's decision to shut the centre.

Over 70 years, generations of schoolchildren have used the Grade II listed Victorian mansion and its 86 acres of land for outdoor learning and residential trips.

But two years ago, the building's owner - the county council - announced it could no longer afford to run it.

It said it had cost the authority more than £270,000 over three years and that £600,000 of maintenance was needed, so the council agreed to shut it.

That was despite a campaign by the Friends of Holt Hall group, although its bid to retain the hall for community use did not prove viable.

Putting it up for sale, the council said it hoped the building could remain as an education centre, rather than becoming a residential home - but that now looks to have been dashed.

More than 20 parties lodged bids, eventually whittled down to three.

The county council is not revealing who the bids were from, but it is understood two were from organisations involved with education.

But one of the parties offered at least £2m more than the rival bidders and the council has agreed to sell the property to them.

The identity of the buyer and the price they have paid has not been revealed as the council says it is commercially confidential.

But it is clearly considerably more than the "offer in excess of" £1.5m guide price sought when Savills marketed the property.

And County Hall has confirmed the buyer intends to use it for private use, rather than as an educational facility.

Greg Peck, cabinet member for commercial services and asset management at Norfolk County Council said: "This sale secures a significant return for Norfolk taxpayers on a property that was losing money every year.”

“We recognise that some of the other proposals could have retained Holt Hall as a centre for education and that this will be disappointing for those who have close ties to the building."

He said the sale would mean an extra £1m could be used to support the education of children across the county and ensure "a lasting legacy”.

Proposals for how that money will be used are being developed by the county’s education and communities teams.

They say they aim to improve the provision for children who cannot attend school, due to ill health, exclusion or for any other reason.

But critics who battled to keep Holt Hall as an education centre criticised the sale.

Steffan Aquarone, Liberal Democrat county councillor for Melton Constable, said: "The county council is simply selling off a priceless community asset for the highest price.

"If I lived in Holt, I’d be deeply concerned the county council has just passed over 84 acres of countryside to either a property developer, or someone with very deep private pockets."

Labour county councillor Mike Smith-Clare, his party's lead for children's services, said: "It’s yet another example of dismal Tory asset stripping in order to make a quick buck.

"This doesn’t meet the needs of our county’s youngsters - it’s just another example of hollow promises, shallow sound bites and a total disregard of Norfolk’s future."

Paul Neale, Green county councillor said: "After 70 years of excellent outdoor learning the county council's educational facility is no more, not because it is not relevant, but because leaders at the council don’t think it worth paying for.

"Of course, it went to the highest bidder with no intentions of continuing its educational heritage."

The council says that when selling an asset it is obliged to seek the ‘best value’.

It says where the difference between two viable bids is more than £2m, the council cannot accept the lower bid without permission from the secretary of state.