Anti-war protestors block the road during a demonstration outside the Houses of Parliament in London, Britain, December 2, 2015. REUTERS/Peter Nicholls

Anti-war protestors block the road during a demonstration outside the Houses of Parliament in London, Britain, December 2, 2015. REUTERS/Peter Nicholls

Anti-war protestors stop a taxi as they block the road during a demonstration outside the Houses of Parliament in London, Britain, December 2, 2015. REUTERS/Peter Nicholls

Anti-war protestors block the road during a demonstration outside the Houses of Parliament in London, Britain, December 2, 2015. REUTERS/Peter Nicholls

Anti-war protestors block the road during a demonstration outside the Houses of Parliament in London, Britain, December 2, 2015. REUTERS/Peter Nicholls

Anti-war protestors block the road during a demonstration outside the Houses of Parliament in London, Britain, December 2, 2015. REUTERS/Peter Nicholls

Anti-war protestors block the road during a demonstration outside the Houses of Parliament in London, Britain, December 2, 2015. REUTERS/Peter Nicholls TPX IMAGES OF THE DAY

A police officer negotiates with an anti-war protestor who has crawled under a lorry outside of the Houses of Parliament in London, Britain, December 2, 2015. REUTERS/Peter Nicholls

Police officers restrain an anti-war protestor after she had crawled under a lorry outside the Houses of Parliament in London, Britain, December 2, 2015. REUTERS/Peter Nicholls TPX IMAGES OF THE DAY

An anti-war protestor blocks the path of traffic outside of the Houses of Parliament in London, Britain, December 2, 2015. REUTERS/Peter Nicholls

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

An anti-war protester demonstrates outside the Houses of Parliament in London, Britain, December 2, 2015. REUTERS/Neil Hall

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

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

Anti-war protesters demonstrate outside the Houses of Parliament in London, Britain, December 2, 2015. REUTERS/Neil Hall TPX IMAGES OF THE DAY

Anti-war protesters demonstrate against proposals to bomb Syria outside the Houses of Parliament in London, Britain December 1, 2015. REUTERS/Neil Hall

Anti-war protesters demonstrate against proposals to bomb Syria outside the Houses of Parliament in London, Britain December 1, 2015. REUTERS/Neil Hall

Anti-war protesters demonstrate against proposals to bomb Syria outside the Houses of Parliament in London, Britain December 1, 2015. REUTERS/Neil Hall

Anti-war protesters demonstrate against proposals to bomb Syria outside the Houses of Parliament in London, Britain December 1, 2015. REUTERS/Neil Hall

Anti-war protesters wave a Syrian flag as they demonstrate against proposals to bomb Syria outside the Houses of Parliament in London, Britain December 1, 2015. REUTERS/Neil Hall

Anti-war protesters demonstrate against proposals to bomb Syria outside the Houses of Parliament in London, Britain December 1, 2015. REUTERS/Neil Hall TPX IMAGES OF THE DAY

Anti-war protesters demonstrate against proposals to bomb Syria outside the Houses of Parliament in London, Britain December 1, 2015. REUTERS/Neil Hall

Protesters demonstrate during a rally held the day before the start of the Paris Climate Change Summit, in London, Britain November 29, 2015. REUTERS/Suzanne Plunkett

A protester wears a polar bear outfit during a rally held the day before the start of the Paris Climate Change Summit, in London, Britain November 29, 2015. REUTERS/Suzanne Plunkett

Protesters demonstrate during a rally held the day before the start of the Paris Climate Change Summit, in London, Britain November 29, 2015. REUTERS/Suzanne Plunkett

Protesters demonstrate during a rally held the day before the start of the Paris Climate Change Summit, in London, Britain November 29, 2015. REUTERS/Suzanne Plunkett

Protesters demonstrate during a rally held the day before the start of the Paris Climate Change Summit, in London, Britain November 29, 2015. REUTERS/Suzanne Plunkett

A traffic jam is seen as cars head towards the approach tunnel of Heathrow Airport, west London, Britain November 26, 2015. Activists opposed to the expansion of London's Heathrow Airport blocked an approach tunnel on Thursday by chaining themselves to a parked vehicle, sowing traffic chaos around Europe's busiest airport. REUTERS/Peter Nicholls

Armed police open the road leading to the approach tunnel to Heathrow Airport, west London, Britain November 26, 2015. Activists opposed to the expansion of London's Heathrow Airport blocked an approach tunnel on Thursday by chaining themselves to a parked vehicle, sowing traffic chaos around Europe's busiest airport. REUTERS/Peter Nicholls

Flight attendants carry their luggage as they walk along the perimeter road leading to the approach tunnel of Heathrow Airport, west London, Britain November 26, 2015. Activists opposed to the expansion of London's Heathrow Airport blocked an approach tunnel on Thursday by chaining themselves to a parked vehicle, sowing traffic chaos around Europe's busiest airport. REUTERS/Peter Nicholls

A protester holds a placard at a demonstration in support of junior doctors in London, in this file photograph dated October 17, 2015. Doctors in Britain's state-funded health service voted on November 19, 2015 to stage their first mass walkout for 40 years in a row over new pay and conditions that they say could put patients in danger. REUTERS/Neil Hall/files

Members of the congregation gather by an altar covered with candles in remembrance of the victims of the Paris attacks, at the French Protestant Church of London in central London, Britain November 15, 2015. REUTERS/Suzanne Plunkett

Members of the congregation listen to a service in remembrance to the victims of the Paris attacks, at the French Protestant Church of London in central London, Britain November 15, 2015. REUTERS/Suzanne Plunkett

A member of the congregation lights a candle in remembrance of the victims of the Paris attacks, at the French Protestant Church of London in central London, Britain November 15, 2015. REUTERS/Suzanne Plunkett

A young boy looks at candles left on an altar in remembrance of the victims of the Paris attacks, at the French Protestant Church of London in central London, Britain November 15, 2015. REUTERS/Suzanne Plunkett

French veterans hold French national flags as members of the congregation place candles on an altar in remembrance of the victims of the Paris attacks, at the French Protestant Church of London in central London, Britain November 15, 2015. REUTERS/Suzanne Plunkett

Members of the congregation listen to a service in remembrance to the victims of the Paris attacks, at the French Protestant Church of London in central London, Britain November 15, 2015. REUTERS/Suzanne Plunkett

A Sikh protester holds up a flag in front of Wembley Stadium which will host an event attended by India's Prime Minister Narendra Modi, in London, November 13, 2015. REUTERS/Toby Melville

Indian Prime Minister Narendra Modi (C) addresses members of parliament and invited guests in the Royal Gallery at the Houses of Parliament in central London November 12, 2015. Britain and India welcomed billions of pounds worth of trade deals during a visit by Indian Prime Minister Narendra Modi, but his arrival on Thursday was overshadowed by protests over a perceived rise in intolerance back home. REUTERS/Justin Tallis/Pool

British Prime Minister David Cameron (C) listens as Indian Prime Minister Narendra Modi (unseen) addresses members of parliament and invited guests in the Royal Gallery at the Houses of Parliament in central London November 12, 2015. Britain and India welcomed billions of pounds worth of trade deals during a visit by Indian Prime Minister Narendra Modi, but his arrival on Thursday was overshadowed by protests over a perceived rise in intolerance back home. REUTERS/Justin Tallis/Pool

Britain's Prime Minister David Cameron looks towards protesters outside Downing Street as he walks with India's Prime Minister Narendra Modi's as they leave 10 Downing Street after their meeting, in London, November 12, 2015. REUTERS/Peter Nicholls

Britain's Prime Minister David Cameron looks towards protesters outside Downing Street as he walks with India's Prime Minister Narendra Modi's as they leave 10 Downing Street after their meeting, in London, November 12, 2015. REUTERS/Peter Nicholls

Demontrators protest opposite Downing Street against India's Prime Minister Narendra Modi's official visit, in London, November 12, 2015. REUTERS/Suzanne Plunkett

A police officer keeps an eye on demontrators protesting opposite Downing Street against India's Prime Minister Narendra Modi's official visit, in London, November 12, 2015. REUTERS/Suzanne Plunkett

Demontrators protest opposite Downing Street against India's Prime Minister Narendra Modi's official visit, in London, November 12, 2015. REUTERS/Suzanne Plunkett

Demontrators protest opposite Downing Street against India's Prime Minister Narendra Modi's official visit, in London, November 12, 2015. REUTERS/Suzanne Plunkett

Demontrators protest opposite Downing Street against India's Prime Minister Narendra Modi's official visit, in London, November 12, 2015. REUTERS/Suzanne Plunkett

Demontrators protest opposite Downing Street against India's Prime Minister Narendra Modi's official visit, in London, November 12, 2015. REUTERS/Suzanne Plunkett

Demontrators protest opposite Downing Street against India's Prime Minister Narendra Modi's official visit, in London, November 12, 2015. REUTERS/Suzanne Plunkett

Demontrators protest opposite Downing Street against India's Prime Minister Narendra Modi's official visit, in London, November 12, 2015. REUTERS/Suzanne Plunkett

Demontrators protest opposite Downing Street against India's Prime Minister Narendra Modi's official visit, in London, November 12, 2015. REUTERS/Suzanne Plunkett

Demontrators protest opposite Downing Street against India's Prime Minister Narendra Modi's official visit, in London, November 12, 2015. REUTERS/Suzanne Plunkett

Demontrators protest opposite Downing Street against India's Prime Minister Narendra Modi's official visit, in London, November 12, 2015. REUTERS/Suzanne Plunkett

Demontrators protest opposite Downing Street against India's Prime Minister Narendra Modi's official visit, in London, November 12, 2015. REUTERS/Suzanne Plunkett

Demonstrators display banners that read "CBI = Voice of Brussels" during a speech by Britain's Prime Minister David Cameron at the Confederation of British Industry (CBI) annual conference in London, Britain November 9, 2015. REUTERS/Toby Melville

A supporter of the activist group Anonymous is detained by police officers during a protest in London, Britain, November 5, 2015. REUTERS/Peter Nicholls

Supporters of the activist group Anonymous face police lines during a protest in London, Britain November 5, 2015. A few thousand protesters took part in the so-called Million Mask March in central London on Thursday. REUTERS/Stefan Wermuth

A supporter of the activist group Anonymous throws a traffic cone towards mounted police officers outside Buckingham Palace during a protest in London, Britain November 5, 2015. A few thousand protesters took part in the so-called Million Mask March in central London on Thursday. REUTERS/Stefan Wermuth

A supporter of the activist group Anonymous is detained by police officers during a protest in London, Britain November 5, 2015. REUTERS/Peter Nicholls

A supporter of the activist group Anonymous is detained by police officers outside the National Gallery during a protest in London, Britain November 5, 2015. REUTERS/Peter Nicholls TPX IMAGES OF THE DAY