London England 2012 Saint Patrick's Day Parade: The Mayor’s St Patrick’s Day Parade and Festival will take place on Sunday 18 March 2012. Set to be one of London's liveliest celebrations of the year, over 100,000 people attended last year's event. The parade, featuring a colourful array of floats, marching bands and groups representing the Irish Counties, will proceed through central London from Green Park to Trafalgar Square starting at 12 noon. Trafalgar Square will host the festival programme of live Irish music and dance on the main performance stage, showcasing the best of Irish music and dance from traditional to contemporary.