Airport expansion is in the arrivals hall but there is plenty of turbulence around the cabinet table

The breaking news today is that there will be a decision.

After years - decades even - of delays over new runway capacity in and around London, Downing Street has announced that something will happen next week.

Quite what that is, we don't know.

But it will be a decision. And not before time.

I have just come from our daily briefing at Downing Street, at which the Prime Minister's spokeswoman announced the arrangements for the decision on new runway capacity in South East England.

The decision is between a third runway at Heathrow, an extended runway at Heathrow or a second runway at Gatwick.

But, as I type, all the indications are that a new runway at Heathrow will be given the green light.

Why do I say this?

In order to placate those around the Cabinet table who are vociferous opponents of Heathrow expansion, the Prime Minister is suspending Cabinet responsibility on this topic 'for a limited period'.

It means ministers will be able to publicly disagree with the decision - rather than being bound by the usual protocol of supporting government policy or resigning from government.

That will allow Foreign Secretary Boris Johnson (who as London Mayor led a bitter campaign against Heathrow) and Education Secretary Justine Greening (whose Putney constituency is under the flight path) to continue to oppose the decision.

Early signs suggest that Heathrow will get to green light to expand Credit: PA

Quite when - and how - ministers subsequently fall back into line, is unclear.

A letter from the Prime Minister setting out the arrangements will be released this afternoon.

Last summer, the Airports Commission recommended - after years of work - that a third runway at Heathrow was in the country's best interests.

And supporters of Heathrow expansion argue that leaving the EU has increased the need for stronger, more frequent connections with new trade partners around the world.

Last week, the Scottish government announced it was supporting Heathrow expansion.

But there are huge - absolutely massive - concerns over air quality and noise pollution in and around the airport.

And the project will involve building one of the runways over the M25.

But to me, this political arrangement means that Heathrow expansion is heading for the arrivals hall - despite the turbulence it will cause.