Today’s announcement that British Airways is to move two of its key US flights – those to Dallas Fort Worth and Houston – from Gatwick to Heathrow marks the start of a radical change at London’s airports.

The move has been on the cards ever since the European Union and the United States signed an Open Skies agreement earlier this year and due to come into force next March.

In the next few months, you can expect a rash of similar announcements. Although British Airways says it has no current plans to move any further services from Gatwick to Heathrow, you can bet BA’s rivals will.

The big problem is slots. In the past there have been very few free slots available at Heathrow. Yet Open Skies gives a big opportunity to those sitting on slots at the airport – bmi in particular, which has an estimated 11% of the slots there – to make money out of them. It seems inconceivable that bmi will use some of these to launch huge numbers of new services from Heathrow but it may very well be convinced to sell some of them at a good price to its partners in the Star Alliance – United Airlines in particular and perhaps even Lufthansa.

It seems inevitable that Heathrow will become even more business-focused in the months to come and Gatwick less so. Given BA’s recent short-haul expansion at London City and rumours of more flights from there, it seems Gatwick is destined to become BA’s – and many other carriers’ - long-haul leisure airport.