From the Wikipedia page [1]:
The Great Stink, or the Big Stink, was a time in the summer of 1858 during which the smell of untreated human waste was very strong in central London.
As the Houses of Parliament were directly on the River Thames and the law courts were also affected, prompt action was seen as a matter of necessity.
The Metropolitan Board of Works were granted sufficient money to undertake the creation of a sewer network, which was done under Joseph Bazalgette.
The Historic England page is [2], and there is much other coverage.