The Parliamentary website describes the efforts to deal with the catastrophe - "By the time fire engines arrived at the burning Houses of Parliament during the fire of 1834, the House of Lords was already destroyed and the Commons was on fire.
The Prime Minister, Lord Melbourne, directed the work to soak the roof of Westminster Hall. The rest of the Houses of Parliament was lost but the hall was saved."
More details - and graphic pictures can be seen at http://www.explore-parliament.net/nssMovies/06/0693/0693_.htm
Today is the anniversary of this great fire.