This article examines the statutory provisions which prohibit unauthorised demonstrations in the vicinity of Parliament Square. The legal position of the pre-existing demonstrator (Mr Brian Haw) is traced back to the decision of Gray J in Westminster City Council v Haw (2002). This case held that Mr Haw had made his home on part of the pavement in Parliament Square and Gray J rejected, one by one, every legal argument which Westminster City Council had used against Haw (such as that he was ‘obstructing’ the highway, or ‘sleeping rough’, or displaying unauthorised advertisements). The decision of the Court of Appeal in R (Haw) v Home Secretary (2006) (which considered the subsequent statutory ban on unauthorised demonstrations) is analysed in the light of the question whether or not that legislation took away Mr Haw’s property rights (and rights under the European Convention of Human Rights) without the payment of compensation. The conclusion is reached that the statutory ban on demonstrations (contained in the Serious Organised Crime and Police Act 2005 and delegated legislation made under it) was ‘hybrid’ in so far as it purported to apply to Mr Haw. In the light of the fact that the ‘hybrid bill’ procedure was not used the article concludes that the Court of Appeal was wrong to interpret the 2005 legislation as if it came into force on the midnight hour of 30 June/1 July 2005 and criminalised the conduct of Haw- a person who could not obtain prior authorisation before starting his demonstration in 2001. Although this article sympathises with the view of the common law that the right of the public to use the highway should be restricted to a right to pass and re-pass for all proper purposes, it concludes that more important property rights than those represented by Mr Haw (including the rights of corporations) will be put at risk if Parliament and the courts forget the warning of the late Professor Christopher Hughes: that “‘the rule of formal generality’ and ‘equality before the law’ is preserved by the distinction between Public and Private Bills.”