Parliament was evacuated this morning for a fire drill, with staff spilling out on to the cold streets.
Hundreds of staff across the whole parliamentary estate were told to leave shortly after 10.30am when the alarm went off.
BBC reporter Vicki Young, who was told to leave the building, tweeted: “The House of Commons has been evacuated while officers investigate a fire alert.”
Photos from Westminster showed huge crowds of people standing outside the building.
A spokeswoman for the House of Commons confirmed an alarm had gone off but was unable to give further details.
Ms Young said the alert was over after around 20 minutes. She tweeted: "Excitement over.
"Staff allowed back into Commons - policeman says it was a drill to check how quickly they could get everyone out."
