Footage posted on social media shows a row breaking out between two men on a London train, in which the Palestine activist threatens to smack the pro- Israel supporter across the head .
The English Defence League founder was detained by dozens of officers near the Royal Courts of Justice, where the rally attended by tens of thousands of people started.
The 61-year-old TV and radio star said that had she still been working for the BBC, she would have had to go on the march, despite knowing that attending rally would mean that she would be fired.