The Unite for Europe march was due to end with a rally in Parliament Square, scene of this week's attack by British-born Islam convert Khalid Masood in which four people died.
Marchers observed a minute's silence in memory of the victims at the start of the demonstration.
In bright sunshine, they waved EU flags and banners with slogans like "So what's the Plan" and "Stop Brexit" as they made their way to parliament. » | Reporting by Ralph Boulton; Writing by Stephen Addison; Editing by Mark Potter | Saturday, March 25, 2017