Police cordoned off the area after the blast in Morpeth Terrace near Victoria station, less than a mile from Parliament. Buildings in the immediate area were damaged but there were no casualties.
The former Tory party chairman Chris Patten, now Governor of Hong Kong, lived in the block until July.
Terry Dicks, Conservative MP for Hayes and Harlington, heard the explosion from his flat about a mile away. 'This is the second blast I've heard from this flat but this was certainly the louder. I am very surprised that the police said it only caused slight damage.'
Seventeen people have been injured and one killed in 15 explosions in London this month.