A band of angry rioters has descended on Parliament in scenes not witnessed in Westminster for a century.
But MPs need not take cover, the 250-strong mob are extras in a major film being shot on the estate.
Suffragette, which tracks the struggle for women to get the vote, stars British favourite Carey Mulligan and features Meryl Streep as fearsome campaigner Emmeline Pankhurst.
Oscar-winning Streep - who in 2011 attended Prime Minister's Questions in preparation for playing Margaret Thatcher in The Iron Lady - has already filmed her scenes and was not expected to be on set.
It is the first time the historic venue has been used for commercial filming, after MPs agreed it was a good way to cover costs.
Scenes have also been shot in Central Lobby and a committee room though not in the Commons or Lords chambers themselves.
With MPs away on their Easter break, the usual ministerial cars were replaced by veteran vehicles and an angry mob of placard-wielding women squaring up to police officers on horseback.
Bemused passing tourists watched through the gates as the apparent noisy protest was easily tamed by regular shouts of "cut".
The filming comes just over 100 years since a series of real demonstrations by members of the Suffragette movement in the Palace of Westminster.
Three unfurled a banner from the Women's gallery - at a time when they were not allowed to sit with male spectators - while two had to be marched off still attached to the grille to which they had chained themselves.
It was filed off in a committee room - but the physical scars of another of the protests remains to this day.
The sword held by Viscount Falkland in a St Stephen's Hall statue was damaged in 1909 when Margery Humes chained herself to it and had to be removed by police using bolt cutters.
Nearby is a plaque commemorating the actions of devoted Suffragette Emily Wilding Davison who hid in a cupboard in the chapel of St Mary Undercroft on the night of the 2011 census in order to register her address as the House of Commons.
Davison was trampled to death by the King's horse when she ran onto the Derby course to make her protest in 1913.
Equal votes for women were not finally granted until 1928.
Scheduled for release in 2015, the film sees Mulligan play a member of the Women's Social and Political Union - and there are also parts for Helena Bonham Carter, Romola Garai, Ben Whishaw, Brendan Gleeson and Anne-Marie Duff.
Sir Alan Haselhurst MP, chair of the House of Commons Administration Committee, said: " As a British film which clearly relates to Parliament's history and heritage, this is an ideal pilot for the House of Commons to identify the opportunities for location filming and income generation.
"We hope the film will engage the public with Parliament's history and heritage, and will offer a new way to bring our iconic buildings to a wider audience."
Adrian Wootton, Chief Executive of Film London and the British Film Commission, said: "Opening up such an iconic location as the House of Commons for filming is fantastic news.
"This unique location promises to attract more production to the capital, and by working with the industry and our partners, we will help ensure it can get the most out of filming, while protecting the integrity of this very special building.
"And I look forward to seeing it on screen in the star studded Suffragette, which will be a fantastic showcase of British talent, behind and in front of the camera, and this very special new location."
Sarah Gavron, director of Suffragette, said: "Our film is inspired by the true stories of the foot soldiers of the Suffragette movement, women who were willing to sacrifice everything in their fight for the right to vote. We are honoured to be allowed to recreate a crucial moment in that long journey towards equality by filming where the Suffragettes actually brought their protest over 100 years ago."
Bonham Carter may not approve of one the more audacious plots hatched by the campaigners for women's votes.
The Government and police were warned in 1909 that one planned to assassinate the then prime minister Herbert Asquith, a staunch opponent of equal suffrage, records released several years ago by the National Archive revealed.
The actress is the former premier's great-granddaughter.