<P> The public right of way along Downing Street has not been extinguished nor subject to a gating order and the road retains the status of a public highway maintained by Westminster City Council . Public access was curtailed by relying on common law powers to prevent breach of the peace (although its legality has been questioned by a correspondent for New Statesman magazine). In 2005 Westminster City Council used anti-terrorism powers contained in the Civil Contingencies Act 2004 to formalise the restrictions by means of a traffic management order . </P> <P> Although the Downing Street government buildings and grounds are a designated site under the Serious Organised Crime and Police Act 2005 for criminal trespass, the street was not included in the boundaries of the designated area . </P> <P> Since 1989, entering Downing Street has required passing through a security checkpoint . The street is patrolled by armed police from the Diplomatic Protection Group, and there is usually at least one police officer outside the front door of Number 10 . Security was tightened after 10 Downing Street was mortar bombed by the IRA in 1991 . </P>

When did downing street close to the public