On this site at 12.15 am on the 25th August 1940 fell the first bomb on the City of London in the Second World War.
The black and white photo showing the lost commemorative board comes from A London Inheritance, a great post covering the area, with many photos taken 1946-54, before the redevelopment of this much-bombed part of the City of London.
Site: First City bomb in WW2 (2 memorials)
EC2, Fore Street, Roman House
The engraved stone is below the window on the ground floor flank wall. Interesting that the stone uses the exact same wording as the commemorative board.