The BBC's Transport Correspondent Tim Hirsch reports

The £80m inquiry has been the longest of its kind in Britain, but a decision is still not expected for more than two years.

By the end of the inquiry, held at The Renaissance Hotel in the airport complex, inspector Roy Vandermeerl had heard from more than 700 witnesses.

Final words

He spoke the last words of the hearing on Wednesday when he said: "Thank you very much, the inquiry is concluded."

Mr Vandermeer, who has become a grandfather twice over since the inquiry started, will now take two years to make his report.

Hefty evidence

It will be based on more than 100,000 pages of daily transcripts, and on documents and letters which would form a pile more than 150ft high.

A fifth terminal could be built

The Department of the Environment will receive the report in around March 2001, and is itself expected to take about nine months before announcing whether the £2bn Terminal 5 can be built.

Mr Vandemeer said: "The task ahead is going to be harder than running the inquiry, but it's a challenge I am looking forward to."

Mr Vandermeer and the government will have to consider the urgent need for airport expansion in south east England, as well as the environmental and congestion concerns of green groups and local authorities.

The airport operator BAA believes the case for the new terminal has been made overwhelmingly at the inquiry, which started in May 1995.

It says the new terminal would lead to only 8% more flights and 3% more road traffic at peak times.

The company has also pointed out that it has asked Mr Vandermeer to recommend to the government that there be no third runway at Heathrow and no increase in noise or night flights if the terminal is built.

BAA has spent about £195m on preparation for the terminal, including the costs of the inquiry and clearing the site.

If the terminal is given the go-ahead, it will take four-and-a-half years to build on the site of a sludge farm.

The earliest possible opening date for the terminal, which would increase Heathrow's annual passenger numbers from 60m to 80m, is 2006.

'Capacity crisis'

BAA has said: "We face an airport capacity crisis and there is no alternative to T5."

BAA spent £195m

But those against the new terminal, including Friends of the Earth (FoE), say more flights and congestion will threaten the quality of life of those living near the airport.

They also point out that 96% of people who have written to the inquiry are against the project.

Local authorities opposed to it have called it "an aggressive proposal" which they say is not fair and does not make sense.

More flights

They say the terminal would mean an extra 160 flights a day in 10 years' time.

FoE believes the government has already decided to agree to the terminal being built.

The group Heathrow Association for the Control of Aircraft Noise has urged the government not to overrule any inquiry recommendation to scrap the scheme.

The inquiry became record-breaking in November 1997, when it went over the 340 sitting days of the 1980s public inquiry into the Sizewell B nuclear power station in Suffolk.

Renaissance Hotel bosses, who hope that the final decision will be announced at their venue, are hosting a farewell party for the inquiry delegates.