By Adam Durbin:
BBC News.
Culture Secretary Lucy Frazer told BBC's Sunday with Laura Kuenssberg the police were right to factor in the scale and global-nature of the event.
MPs and human rights groups have criticised the police after 52 people were arrested in London on Saturday.
The Metropolitan Police said it acted in a "proportionate manner".
Among those held was the head of the anti-monarchy group Republic, Graham Smith. He was released on Saturday evening after 16 hours in custody and said there was "no longer a right to peaceful protest in the UK".