Feilden+Mawson acted as conservation and historic buildings consultants, advising the design team on alterations to Trafalgar Square as part of the 'World Squares for All' project, including the designs for the new central stairway and the new lift enclosure pavilions.

This project resulted in various honours, including the RIBA London Award 2004, European Union Prize Cultural Heritage Europa Nostra 2004, Civic Trust Hard Landscaping Award 2004 and the RIBA London/English Heritage Award for Building in an Historic Context 2004.