What are the restrictions on holding public procession at UK Parliament?

There are certain restrictions on holding public processions at the UK Parliament, which are in place to ensure the safety and security of the parliamentary estate and the people who work and visit there. The restrictions are enforced by the Metropolitan Police, which has responsibility for security around Parliament. The main restriction on public processions at the UK Parliament is that they are not allowed to pass through the parliamentary estate itself. This includes the area known as the Parliamentary Square, which is directly in front of the Palace of Westminster and contains the statue of Winston Churchill and the Cenotaph war memorial. In addition, the police may impose further restrictions on public processions in the vicinity of Parliament if they believe that there is a risk of public disorder or other disruption. This may include restricting the route of the procession, limiting the number of participants, or imposing other conditions on the conduct of the procession. It is also worth noting that the Palace of Westminster is a UNESCO World Heritage Site and a Grade I listed building, and as such is subject to strict rules regarding the preservation of its historic fabric and appearance. Any public procession in the vicinity of Parliament must therefore take into account the need to protect the architectural and cultural significance of this historic building.