On 7 July2005 as part of the 7/7 London Bombings, a bomb exploded on a double-decker bus in the north-east corner of the square, outside the BMA building. This resulted in 13 fatalities.
On the occasion of the first anniversary in 2006, the Department for Culture, Media and Sport announced that the square would be the site of the permanent national memorial. A memorial garden is to be laid out in part of the existing garden and the BMA has commissioned a commemorative sundial.