Conservative MP Tobias Ellwood stands amongst the emergency services at the scene outside the Palace of Westminster, London, after policeman has been stabbed and his apparent attacker shot by officers in a major security incident at the Houses of Parliament. (Photo by Stefan Rousseau/PA Images via Getty Images)
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PA Images Stefan Rousseau - PA Images

Conservative MP Tobias Ellwood (bottom right) stands amongst the emergency services at the scene outside the Palace of Westminster, London, after policeman has been stabbed and his apparent attacker shot by officers in a major security incident at the Houses of Parliament. (Photo by Stefan Rousseau/PA Images via Getty Images)
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PA Images Stefan Rousseau - PA Images

Emergency services at the scene outside the Palace of Westminster, London, after policeman has been stabbed and his apparent attacker shot by officers in a major security incident at the Houses of Parliament. (Photo by Stefan Rousseau/PA Images via Getty Images)
Getty Images

PA Images Stefan Rousseau - PA Images

Emergency services at the scene outside the Palace of Westminster, London, after policeman has been stabbed and his apparent attacker shot by officers in a major security incident at the Houses of Parliament. (Photo by Stefan Rousseau/PA Images via Getty Images)
Getty Images

PA Images Stefan Rousseau - PA Images

Emergency personnel close to the Palace of Westminster, London, after policeman has been stabbed and his apparent attacker shot by officers in a major security incident at the Houses of Parliament. (Photo by Yui Mok/PA Images via Getty Images)
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PA Images Yui Mok - PA Images