Complex sentence: In 2006 the Corporation of London changed its name to the "City of London Corporation", when the title Lord Mayor of the City of London was reintroduced, partly to avoid confusion with the Mayor of London.
Split into simpler sentences: In 2006 the Corporation of London changed its name to the "City of London Corporation". At the same time the title Lord Mayor of the City of London came into use, partly to avoid confusion with the Mayor of London.