The St Paul's Watch was a voluntary organisation originally formed during World War One and reformed during the Second World War. The group protected the Cathedral from bombing raids by reporting any instances of gunfire, incendiaries or damage to the London Fire Brigade, and the members received training on dealing with these issues themselves. The Watch were made up of members from various backgrounds and professions, such as members of the clergy, architects and civil servants. The high quality of talent in the group saw it dubbed 'the best club in London'.
This badge would have been proudly worn by such members.