New figures appear to undermine the economic arguments for the controversial expansion of Heathrow airport.
They show that the airport's recent growth is almost entirely caused by transit passengers, and are published as the Labour peer Lord Soley launches an industry-wide pressure group for expansion at Heathrow.
Lord Soley, a former chairman of the parliamentary Labour party, is to be the head of Future Heathrow, a lobby group bringing together unions, airlines and the Con federation of British Industry in support of a third runway at the world's largest international hub.
Future Heathrow's inaugural meeting in London is to be picketed by west London residents who live under the airport's flightpath.
In an opening shot against the new body, protesters published research suggesting that the proportion of passengers at Heathrow who spend only a few hours on the ground has shot up in recent years.
According to the anti-noise group Hacan ClearSkies, annual passenger traffic at the airport rose by 22 million to 67 million between 1992 and 2004. But 19 million of the extra travellers were in transit.
Hacan points out that these people pay no air passenger duty and contribute virtually nothing to London's regional economy. The proportion of transfer traffic at Heathrow has risen from 9% to 35% over 12 years.
Airlines maintain that attracting transfer passengers allows them to offer a wider range of destinations. But the range of destinations from Heathrow has fallen from 200 to 170 over 13 years and is now below the 184 routes on offer from Gatwick airport.
