The Extinction Rebellion (XR) environmental protesters have identified Heathrow Airport as their next target, having spent four days camped out in central London.

Here, the Press Association looks at how the protest might work.

– Why Heathrow?

A Heathrow Airport sign
Heathrow is the country’s largest airport (Steve Parsons/PA)

No explanation has been given – except for a peculiar press release which consisted almost entirely of quotes from Sir David Attenborough on climate change.

But it is an obvious target. The airport is the country’s largest, yet is currently operating at 98% capacity, it said. Plans to expand have been met with concern from environmentalists.

– What form will the protest take?

Details are typically vague at the moment – an element of surprise is often crucial for a well-executed stunt.

So far, the XR protesters have favoured obstruction of roads, sit-ins, and supergluing themselves to other things.

– What sort of penalties could a protester expect?

Those accused of obstructing trains in Canary Wharf this week were told they could face up to two years in prison.

At airports, the penalty can be much more severe.

Pilots who flout restrictions banning all drones from flying within one kilometre of airport boundaries face an unlimited fine, up to five years in prison, or both.

The Aviation and Maritime Security Act 1990 also states it is illegal for someone to disrupt the services of an airport that could endanger the safe operation or safety of passengers and staff.

The punishment? Potentially life in prison.

– That must be a deterrent?

Some of the Stansted 15 outside Chelmsford Crown Court after sentencing
Some of the Stansted 15 outside court after sentencing (John Stillwell/PA)

Recent cases have looked slightly more favourably than that on protesters at airports.

The so-called Stansted 15, who cut through the airport’s perimeter fence and locked themselves together around a Boeing 767 jet containing people being deported to Africa in 2017, avoided a jail term when they were convicted at trial.

Each defendant denied the single charge against them but all were found guilty following an earlier two-month trial at Chelmsford Crown Court, with prosecutor Tony Badenoch QC telling jurors the activists put the “safety of the airport in a likelihood of danger”.

Once again, XR will be looking for “arrestables” – those who are willing to be detained by police in the course of publicising their message.

– What is Heathrow Airport doing to pre-empt the protest?

Unlike many previous airport protests, Heathrow has at least been notified in advance.

A spokesman confirmed they were “working with the authorities to address any threat of protests which could disrupt the airport”.

They added that passengers should contact their airlines for up-to-date information ahead of their flights.

– What about the other protests in London?

Demonstrators during an Extinction Rebellion protest Marble Arch, London
An Extinction Rebellion protest at Marble Arch (Yui Mok/PA)

There is nothing to suggest the sit-ins at Marble Arch, Oxford Street, Waterloo Bridge and Westminster will be pared back – in fact organisers have claimed “thousands” more are ready to flock to London over the weekend.

It may be that a splinter group heads to Heathrow, leaving the remainder to protest in central London as originally planned.

– So will the Heathrow protest definitely go ahead?

Who knows.