The cost of repairing and upgrading schools has been put at a staggering pound;1 billion by Peter Peacock, Deputy Children and Education Minister. It is four times earlier estimates, and one-third of the total estimated backlog south of the border.

The minister acknowledged the scale of the Scottish problem on Monday at his latest consultation meeting on the education bill in Inverness.

In Highland, where Mr Peacock spent 17 years as a councillor and rose to convener, the council needs pound;78 million to make schools wind and watertight.

Maryburgh primary, for instance, is not even on Highland’s waiting list for schools needing urgent upgrading, although most of the school is housed in 35-year-old huts. Windows are rotten, roofs leak, green damp creeps up walls and pupils have to cross the playground to go to the toilet.

Lorna Moodie, headteacher of the 152-pupil school, complained: “It’s very difficult to get a feel for the fact that you’re one school.” Displaying pupils’ work was difficult.

Sandy MacKenzie, SNP leader and local councillor, said no significant work had been done in recent years, apart from minor repairs to things like leaking roofs. “You can do a patch and repair job, give it a lick of paint and make it wind and watertight, but there ‘s nothing to enhance the quality of education for the children,” he said.

Bruce Robertson, director of education, last week warned Highland’s education committee that “the biggest issue in standards of education is the standard of the accommodation young people are educated in”.

Mr Peacock this week admitted: “This is a legacy of the neglect of capital investment since the mid-1970s. The backlog of work is truly colossal. There is probably the best part of one thousand million pounds of work needing to be done. We have been trying to put more money in. We have relaxed capping rules on local authorities, giving them flexibility to spend on maintenance of schools if they so choose. We are looking at public-private partnerships as well. This will not satisfy people, but I am not going to kid anyone that this can be sorted in the short-term. It’s a long haul to sort this out.”

Mr Peacock added: “Highland Council is spending twice as much this year in its capital programme. Money is flowing in but the scale of the problem is so large. We will continue to argue within government for the share of money that we think needs to go on that.”

Since they came to power two and a half years ago, ministers have announced plans to inject around pound;300 million into school building works.

Another pound;400 million has been committed through public-private partnerships. Nine authorities have signed up to repair and build schools through the controversial scheme.

Mr Robertson has been shocked by the extent of the problems since he took over last year. He told councillors: “We cannot wave a magic wand. But making schools wind and watertight and providing a safe environment are the absolute minimum.”

Michael Foxley, Liberal Democrat councillor, said: “In Lochaber, we need five new-build schools at a cost of pound;15 million - but I think it’s closer to pound;20 million. The scale of what’s required to catch up is probably pound;100 million in Highland.”

Officials estimate one-third of Highland’s 220 schools need major upgrades and the rest require significant work. Spending on capital projects has more than doubled since the last years of the Tory Government, to around pound;8 million a year.

The council is also planning to build four new schools under the public-private partnership scheme, costing pound;77 million over 25 years.