Smithfield was a place of execution for many years and was the site of the execution of William Wallace. In 1955 a request to install a memorial to Wallace on the screen wall of the hospital in West Smithfield was approved by hospital authorities, and the memorial, which several coloured crests and cartouches, including two St Andrews flags, was unveiled on 8 April 1956.
The plaque on the wall of the hospital next to that for William Wallace commemorates the death by fire of Protestant martyrs during the reign of Mary I (1553-1558). The plaque was erected in 1870 by the Protestant Alliance of London. It was supported by the Governors of the hospital at the request of the Reverend John Wright in 1868.
A third plaque, to the Peasants Revolt, which took place at Smithfield, was unveiled on the screen wall in 2015.