The Fourth plinth is the northwest plinth in Trafalgar Square in central London. It was originally intended to hold an equestrian statue of William IV, but remained bare due to insufficient funds. For over 150 years the fate of the plinth was debated; in 1998, the Royal Society for the encouragement of Arts, Manufactures and Commerce commissioned three contemporary sculptures to be displayed temporarily on the plinth. Shortly afterwards, Chris Smith, Secretary of State for Culture, Media and Sport, commissioned Sir John Mortimer to seek opinions from public art commissioners, critics and members of the public as to the future of the plinth.
Mortimer's final report recommended that the commissions remain a rolling programme of temporary artworks rather than settle permanently on one figure or idea to commemorate. In 2003, the ownership of Trafalgar Square was transferred from Westminster City Council to the Mayor of London and this marked the beginning of the Mayor of London's Fourth Plinth Commission as it is now known.