The motto Sub Cruce Candida (Under the White Cross) belongs to the Danish Order of Dannebrog, so what is it doing above the old military hospital that Tate Britain now uses as offices?
The answer is that Queen Alexandra, wife of King Edward VII, was Danish and chose the motto herself when she became president of the Imperial Military Nursing Service. Note the Dannebrog cross interlinked with the letter A on the shield in the pediment. The red brick and Portland stone edifice, typical of the bombastic Edwardian style, was built in 1906.
Apparently, the King was visiting the hospital and a cook carrying a huge bowl of custard bustled through a door and tipped the lot over him. I bet that Queen Alexandra, one of the most betrayed and most long-suffering wives in history, laughed like a Dane.