Some of the country’s most valuable historic sites and buildings are under threat because English Heritage is unable to cope with a massive “conservation backlog”.
Tens of millions of pounds are needed to ensure that several sites are not closed to the public because they have fallen into disrepair, ministers warned.
Historic buildings under threat include Stevens Mill in Burwell, Cambridgeshire, and Doddington Castle and Stanlow Abbey in Cheshire.
The Coalition has announced plans to split English Heritage, which runs 440 historical sites, into an independent charitable trust that will keep its present name.
Officials believe that charitable status give it more freedom to raise and invest money and attract other funding.
The rest of the organisation – dealing with planning applications and protecting historic buildings – will remain part of government and is likely to take on the name “Historic England”.
In a consultation, ministers said that if a new funding model was not found for the organisation, there would be an “accelerated loss of historic fabric in public ownership”.
The document warns that if nothing is done, some of Britain’s most important sites could fall into disrepair and that membership of the organisation could decrease.
“Without the new model and the additional funding, the National Heritage collection would not be able to plan long term for the future nor effectively address the conservation defects backlog,” the report states.
“The backlog of conservation defects would continue to increase, resulting in an accelerated loss of historic fabric in public ownership.
“This would also have a negative effect on perception of the brand and make attendance and membership hard to sustain and impossible to grow.”
It adds: “Lack of significant investment in the properties would compound the problem of the deteriorating condition of the collection with a damaging impact on attendances and income.”
The organisation’s conservation budget was frozen a decade ago which has left parts of the collection in disrepair.
At least £52 million is needed to tackle the conservation defects across English Heritage sites.
As part of the new plans for the organisation, the Government plans to give it an £80 million payment in 2015 so that the body can carry out major refurbishments at many of its sites.
Announcing the consultation at the start of the month, Maria Miller, the Culture Secretary, said: “Our historic buildings are loved by everyone, and act as a magnet for tourists from all over the world. English Heritage sites such as Stonehenge, Hadrian’s Wall, Tintagel Castle and Battle Abbey are at the very heart of what England is all about.
“As such we want to be able to give them the tools they need so they can generate their own income.”