A bomb which fell on London Bridge in 1940 during the Blitz of World War II blew out all the windows and damaged the plasterwork and the roof of the north aisle. However, the church was designated a Grade I listed building on 4 January 1950 and repaired in 1951, being re-opened for worship in June of that year by the Bishop of London, William Wand. The architect was Laurence King. "At St Magnus the Martyr almost the whole of the plaster work had to be reproduced. Fortunately, as in some other cases, the furniture had been safely stored, but against £16,000 only £9,000 was recoverable." Restoration and redecoration work has subsequently been carried out several times, including after a fire in the early hours of 4 November 1995. Cleaning of the exterior stonework was completed in 2010.