The act of defiance came as pressure increased from Tory MPs for a dedicated "safe area" close to the Palace of Westminster in which broadcast interviews could be conducted with ministers and MPs.
The police were forced to apologise for taking 20 minutes to respond to frantic 999 calls from Alan Duncan MP, the chairman's parliamentary aide, after Dr Mawhinney was accosted on College Green on his way to interviews after the State Opening of Parliament.
The Commons Sergeant at Arms is expected to hold an inquiry into the possibilities of a dedicated press area.
Betty Boothroyd, the Speaker, was said yesterday to have been concerned about possible risks to safety since the leadership contest in the summer, when the green was in constant use for media interviews.
Authorities at Kingsway College, Holborn, moved quickly to distance themselves from the holding of the news conference on its premises, saying it was convened in the canteen by Nick de Marco, student union president at Kingsway and an organiser of the Movement for Justice, which was behind the paint-throwing.
Two A-level students at the college, Karen Doyle and Naveed Malick, both 18, were arrested for assault on Wednesday, along with Amanda Egbe, 20, a sabbatical officer on the student union of the University of North London. Charges had not been brought last night.
Mr de Marco said the protest "was a declaration of war against the Government. If it tries to introduce the most racist Bill ever and send people back to their deaths, we will stop it in any way necessary."Reuse content