" Memorial stone with carved inscription set beneath a carved royal coat of arms (lion, crown and shield and the motto, 'Dieu et mon Droit'). On either side of the coat of arms is a carved stone representation of a rectangular tower.
50th Anniversary of Victoria's reign and the building of Tower Bridge" ~ http://www.pmsa.org.uk/pmsa-database/3178/
Loaction:
https://goo.gl/maps/KCxqPBMzKP72