An anti-Heathrow airport expansion protest sign is seen in the threatened village of Sipson, adjacent to the airport in London, Britain July 1, 2015. REUTERS/Peter Nicholls/File Photo

Badges and beer mats, protesting at the proposed expansion of Heathrow airport, are seen inside a pub in the village of Harmondsworth, adjacent to the airport in London, Britain July 1, 2015. REUTERS/Peter Nicholls/File Photo

A steel worker protests outside of the Houses of Parliament in London, Britain in this October 28, 2015 file photo. REUTERS/Toby Melville/Files

British steel workers protest outside of the Houses of Parliament in London, Britain in this October 28, 2015 file photo. REUTERS/Toby Melville/Files

A police officer stands between rows of taxis during a protest by London cab drivers against Uber in central London, February 10, 2015 REUTERS/Stefan Wermuth

A police officer stands between rows of taxis during a protest by London cab drivers against Uber in central London, February 10, 2015 REUTERS/Stefan Wermuth

A police officer stands between rows of taxis during a protest by London cab drivers against Uber in central London, February 10, 2015 REUTERS/Stefan Wermuth

A police officer stands between rows of taxis during a protest by London cab drivers against Uber in central London, February 10, 2015 REUTERS/Stefan Wermuth

A police officer stands between rows of taxis during a protest by London cab drivers against Uber in central London, February 10, 2015 REUTERS/Stefan Wermuth TPX IMAGES OF THE DAY

A London cab driver wears a Star Wars themed costume during a protest against Uber on Whitehall in central London, February 10, 2015 REUTERS/Stefan Wermuth

A London cab driver waves a Union flag as he stands on the bonnet of his taxi during a protest against Uber on Whitehall in central London, February 10, 2015 REUTERS/Stefan Wermuth TPX IMAGES OF THE DAY

A London cab driver waves a Union flag as he stands on the bonnet of his taxi during a protest against Uber on Whitehall in central London, February 10, 2015 REUTERS/Stefan Wermuth

A London cab driver holds up a sign outside Downing Street during a protest against Uber on Whitehall in central London, February 10, 2015 REUTERS/Stefan Wermuth

A London cab driver waves a Union flag as he stands on the bonnet of his taxi during a protest against Uber on Whitehall in central London, February 10, 2015 REUTERS/Stefan Wermuth

A London cab driver waves a Union flag as he stands on the bonnet of his taxi during a protest against Uber on Whitehall in central London, February 10, 2015 REUTERS/Stefan Wermuth TPX IMAGES OF THE DAY

A London cab driver waves a Union flag as he stands on the bonnet of his taxi during a protest against Uber on Whitehall in central London, February 10, 2015 REUTERS/Stefan Wermuth

A London cab driver waves a Union flag as he stands on the bonnet of his taxi during a protest against Uber on Whitehall in central London, February 10, 2015 REUTERS/Stefan Wermuth

Protestors in London, Britain December 12, 2015 take part in a demonstration against bombing Syria. REUTERS/Neil Hall

Protestors in London, Britain December 12, 2015 take part in a demonstration against bombing Syria. REUTERS/Neil Hall

Protestors in London, Britain December 12, 2015 take part in a demonstration against bombing Syria. REUTERS/Neil Hall

Protestors in London, Britain December 12, 2015 hold placards as they take part in a demonstration against bombing Syria. REUTERS/Neil Hall

Protestors in London, Britain December 12, 2015 take part in a demonstration against bombing Syria. REUTERS/Neil Hall

Protestors in London, Britain December 12, 2015 wave Syrian flags as they take part in a demonstration against bombing Syria. REUTERS/Neil Hall

Protestors in London, Britain December 12, 2015 take part in a demonstration against bombing Syria. REUTERS/Neil Hall

Anti Heathrow expansion activists at the 'Grow Heathrow' protest camp in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls

Anti Heathrow expansion activists at the 'Grow Heathrow' protest camp in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls TPX IMAGES OF THE DAY

Posters against Heathrow expansion hang at the 'Grow Heathrow' protest camp in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls

Anti-Heathrow expansion activists walk through the 'Grow Heathrow' protest camp in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls TPX IMAGES OF THE DAY

An anti-Heathrow expansion activist and a child walk through the 'Grow Heathrow' protest camp in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls

The kitchen area dish washing bench at the 'Grow Heathrow' protest camp is seen in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls

Anti-Heathrow expansion activists sit in the 'Grow Heathrow' protest camp in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls TPX IMAGES OF THE DAY

Road signs close on the approach road to Heathrow airport can be seen from the anti-Heathrow expansion activists', 'Grow Heathrow' protest camp, in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls

Anti-Heathrow expansion activists sit in the 'Grow Heathrow' protest camp in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls

A painted mural at the 'Grow Heathrow' is seen at the protest camp in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls

The entrance gate to the 'Grow Heathrow' protest camp is seen in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls

An anti-Heathrow expansion activist washes clothes in a washing machine operated by pedal power, at the 'Grow Heathrow' protest camp in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls

The perimeter fence protecting the 'Grow Heathrow' protest camp is seen in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls

An old van and makeshift hut at the at the 'Grow Heathrow' anti-airport expansion protest camp in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls

The entrance of the 'Grow Heathrow' protest camp is seen in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls

The 'Grow Heathrow' protest camp is seen through a fence in the village of Sipson, seen through its' perimeter fence, near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls

Anti Heathrow expansion activists walk through the 'Grow Heathrow' protest camp in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls

Tree houses are seen at the 'Grow Heathrow' protest camp in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls

Anti-Heathrow expansion activists chat at the 'Grow Heathrow' protest camp in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls

Anti-Heathrow expansion activists walk through the 'Grow Heathrow' protest camp in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls

Anti-Heathrow expansion activists sit at the 'Grow Heathrow' protest camp in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls

Anti Heathrow expansion activists arrive at the 'Grow Heathrow' protest camp in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls

Anti-Heathrow expansion activist sits in a tree house at the 'Grow Heathrow' protest camp in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls

An anti Heathrow expansion activist chops wood at the 'Grow Heathrow' protest camp in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls

A woman walks through communal area at the anti-Heathrow expansion activists', 'Grow Heathrow' protest camp in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls

An anti-Heathrow expansion activist overlooks the 'Grow Heathrow' protest camp in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. REUTERS/Peter Nicholls

Anti-war protesters hug after the British parliament voted in favour of air strikes against militants in Syria, during a demonstration outside the Houses of Parliament in London, Britain, December 2, 2015. REUTERS/Peter Nicholls TPX IMAGES OF THE DAY

An anti-war protester cries after the British parliament voted in favour of air strikes against militants in Syria, during a demonstration outside the Houses of Parliament in London, Britain, December 2, 2015. REUTERS/Peter Nicholls

Anti-war protestors gesture after the British parliament voted in favour of air strikes against militants in Syria, during a demonstration outside the Houses of Parliament in London, Britain, December 2, 2015. REUTERS/Peter Nicholls

An anti-war protestor cries after the British parliament voted in favour of air strikes against militants in Syria, during a demonstration outside the Houses of Parliament in London, Britain, December 2, 2015. REUTERS/Peter Nicholls

An anti-war protestor cries after the British parliament voted in favour of air strikes against militants in Syria, during a demonstration outside the Houses of Parliament in London, Britain, December 2, 2015. REUTERS/Peter Nicholls

An anti-war protestor cries after the British parliament voted in favour of air strikes against militants in Syria, during a demonstration outside the Houses of Parliament in London, Britain, December 2, 2015. REUTERS/Peter Nicholls TPX IMAGES OF THE DAY

Anti-war protesters demonstrate outside the Houses of Parliament in London, Britain, December 2, 2015. REUTERS/Peter Nicholls

Police stand guard as anti-war protestors demonstrate outside the Houses of Parliament in London, Britain, December 2, 2015. REUTERS/Peter Nicholls

Police stand guard as anti-war protestors demonstrate outside the Houses of Parliament in London, Britain, December 2, 2015. REUTERS/Peter Nicholls

A statue of former Prime Minister Winston Churchill is seen beside anti-war protestors as they block the road during a demonstration outside the Houses of Parliament in London, Britain, December 2, 2015. REUTERS/Peter Nicholls