In the condolence book David Cameron wrote:
This was a deeply shameful event in British history, one that Winston Churchill rightly described at the time as 'monstrous'.
We must never forget what happened here, and in remembering we must ensure that the United Kingdom stands up for the right of peaceful protest around the world.
More top news
Actress will play Belle in a live-action remake of Disney's animated Beauty and the Beast.
ITV News hears the remarkable story of a Holocaust survivor who went on to marry the British soldier who liberated her from Bergen-Belsen.
A touch brighter to the southeast but still a great deal of cloud cover across the UK with patchy rain in the west.