5th December 1952 marked the start of the horrific Great Smog of London. The smog triggered the process that led to the Clean Air Act in 1956. During the following 5 days, 4000 lives were lost followed by a further 8000 in the following weeks. 1/n

https://twitter.com/BBCArchive/status/1731938960262209561

During the day on 5 December, the fog was not especially dense and generally possessed a dry, smoky character. When nightfall came, however, the fog thickened. Visibility dropped to a few metres. The following day, the sun was too low in the sky to burn the fog away. 2/n