By 2010 that figure could have risen to 13.6 million as passengers desert the airlines for rail services to the Continent offering cheaper fares and the same journey times.
The analysis by the Department of Transport says the lucrative air routes between London and Paris, Brussels and Amsterdam, dominated by British Airways and British Midland, would be hardest hit. Last year 6.75 million passengers flew on these three routes.
In the longer term, the DoT says as many as 77 per cent of air passengers between London and Paris and 83 per cent of those flying between London and Brussels could switch to rail.
But other European air destinations such as Rotterdam, Cologne, Dusseldorf, Frankfurt and Geneva would also be affected, along with some short-haul European routes served from Birmingham and Manchester airports.
Assuming that the high-speed Channel tunnel rail link from London to the Kent coast is in service by 2003, the DoT study estimates that 1.8 million business passengers and 4.2 million leisure travellers will be using trains instead of planes by next year. Those figures would rise to 5.2 million and 8.4 million respectively by 2010. Even if the high-speed link is not built before 2010, 8 million passengers would divert to rail.
In France the state-owned railway SNCF cleaned up when it launched TGV services on routes such as Paris-Lyon, offering fares 30 to 50 per cent lower than those charged by the airlines.
The study says that the differential between air fares and fares on Channel tunnel rail services will be smaller. It also says that the number of business passengers switching to rail will tail off rapidly where the train journey is longer than three to four hours. But there will still be a 'substantial diversion' of leisure passengers.
The Channel tunnel is due to open in May with Eurostar passenger services introduced in the autumn. Initial journey times will be three hours from London to Paris and 2 hours 40 minutes from London to Brussels. The TGV line between Lille and Brussels is scheduled to open in 1996 cutting journey times further while high- speed lines are expected to be in operation between Brussels and Amsterdam by 2002.