The forest, lying between the valleys of the Wye and the Severn and the most ancient hunting forest in England, is facing the threat of giant limestone quarries which may have to be dug to meet the Government's massive target for crushed rock for the roads and construction industries.
The adjacent Wye Valley Area of Outstanding Natural Beauty is also at risk.
The specific and unambiguous promise of special protection was given personally by the then shadow environment secretary, Frank Dobson, at a meeting in the forest one month before the election last year.
Mr Dobson's pledge was put out on an official Labour Party press release and featured prominently in the election literature of the Labour candidate for the Forest of Dean, Diana Organ.
Local campaigners feel it helped her capture, with a lower than average swing to Labour, what had been a Tory-held constituency (as Gloucestershire West) for 18 years.
However, Mr Dobson switched briefs to health after the election and at two meetings in the past six months the environment department's planning minister, Richard Caborn, has made it clear the Government has no intention of setting up the special protection regime Mr Dobson promised.
A spokesman for the Department of the Environment, Transport and the Regions said yesterday: "Richard Caborn has met Diana Organ and local delegations. There is no immediately available one-off solution for the forest."
Instead, campaigners against the quarrying threat are being told to work through the traditional planning process. Local people, who last month delivered 8,000 postcards to Downing Street asking Tony Blair when the promise was going to be kept, are now talking hotly of betrayal.
Bill Hobman, Labour chairman of the Forest of Dean district council, said: "I do have to say I am extremely disappointed that what was a categorical statement made without us asking, which I take to be an election pledge, is not being honoured by the minister."
Ken Secrett, a resident who founded Hewelsfield Against Quarrying, one of a number of pressure groups, said: "The Labour Party gave a simple straightforward promise of custom-built special planning status for the forest, which undoubtedly won many votes and influenced the election result in a marginal constituency. Now the Government seems determined to renege on its promise and I think it is a disgusting betrayal.
"It reinforces the cynicism in which politicians are held in this country."
The Forest of Dean, which was considered for designation as Britain's first national park in 1938 but was left for the Forestry Commission to protect, was once notable for coal mines and other industrial sites.
But tourism now underpins its economic future.
The threat to the forest and Wye valley comes from the Government's policy for minerals planning, still based on the outdated "predict and provide" approach - work out how much you think you will need and then try and provide it, whatever the consequences - which John Prescott, Deputy Prime Minister, abandoned for housing policy earlier this year.
"Predict and provide" means the Government is chasing a target of 1.9 billion tons of crushed rock for the roads and construction industries by 2006 and Gloucestershire County Council has been told to find 22.4 million tons as its share by that date - which it cannot do at present extraction rates.
Six months before the election the county council selected several parts of the forest as areas of search for limestone quarries, sparking a protest from residents who feared not only massive new scars on the landscape but pressure from lorries on the forest's minor roads.
Mr Dobson responded at a public meeting at Clearwell Castle in the forest in April last year. Accompanied by Mrs Organ, he said: "Today the Forest of Dean is faced with proposals for mineral workings, in particular limestone quarrying on a scale which poses a major threat ... the time has come to offer special planning protection to the Forest of Dean. We don't propose simply to apply any of the existing special categories of protection. We propose instead to offer the Forest of Dean a new 'custom-built' special status appropriate to its unique status and character."
There were precedents for Mr Dobson's promise: such custom-built planning status has already been given to other areas, including the Norfolk Broads and the New Forest. Mr Caborn, however, has shown no interest. Mr Dobson also promised a sweeping consultation exercise about the plan after the election - which has not taken place either. Mrs Organ has led two delegations of local people to see Mr Caborn about Mr Dobson's promise and received, in effect, a dusty answer. She was not available for comment yesterday.
The Government is to publish a White Paper on the future of the countryside later in the year. Michael Meacher, the environment minister, said it will set out a "new vision" of rural life.