https://www.bbc.co.uk/news/uk-england-london-68991038
Reverend Sue Parfitt, 82, and Judy Bruce, 85, a retired biology teacher, targeted the glass enclosure around the historic document on Friday.
The pair then held up a sign reading "The Government is breaking the law" before gluing themselves to the display, footage posted online shows.
The British Library said security had "intervened to prevent further damage".
The Metropolitan Police said two people had been taken into custody having been arrested on suspicion of causing criminal damage.