Proposals for a second runway at Gatwick are expected to be dismissed when a Government report is published tomorrow.
Transport Secretary Alistair Darling will confirm there are no plans to build on the site before 2019, despite the desperate need to meet increasing runway slots in the South-East.
He is likely to suggest Heathrow is the preferred site to be developed under plans for major expansion of Britain's airports with another runway planned at Stansted.
A new runway could be built at Gatwick after 2019 when a legal agreement drawn up to prevent expansion has expired.
Brendon Sewill, of the Gatwick Area Conservation Campaign, which has been fighting any expansion since the idea was first proposed in 1952 because of the environmental impact on the area, was delighted.
He said: "We will wait to see what the report says but if this suggestion is true then we think that it is absolutely right that the Government respect the legal agreement.
"It emphasises the agreement is not just a bit of paper but reflects the difficulty of finding the space to put a second runway at Gatwick."
Earlier this year, it was claimed the Government had found a way round the agreement signed by West Sussex County Council and the British Airports Authority (BAA) in 1979.
The deal was signed with BAA because of alarm sparked by proposals for a second Gatwick terminal. Local residents believed a second terminal meant another runway.
However, the consultation document will say Ministers have no plans to break the agreement.
No development will take place at Gatwick for the foreseeable future, it will state.
Mr Sewill said: "We are not going to relax our guard at present. We trust the report is accurate but it is only a consultation paper and they could change their minds."
A spokeswoman for Crawley MP Laura Moffatt said although she had not had a chance to comment on the consultation paper, she had not supported a second runway in the past.
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