Lindsay Hoyle, a Commons deputy speaker, urges colleagues to take precautions.

Ukip, Tommy Robinson, the UK “yellow vests”, Democratic Football Lads Alliance and Leave Means Leave campaign are holding rallies in the capital, on the day Britain was due to leave the EU.

The self-styled “yellow vest” protester James Goddard has denied calling the MP Anna Soubry a Nazi and a traitor, during a chaotic court hearing in which the judge adjourning proceedings partway through.

Pro-Brexit protesters blocked the roads around Parliament on Saturday as activists launched a second consecutive day of demonstrations at Westminster.