Today in 1952, sunshine returned to  London following four days of dense fog in which London transport was brought to a standstill.  The atrocious conditions led to widespread disruption of rail, road and air services and affected shipping on the River Thames.  As freshening winds and milder temperatures dissipated the fog, London buses and coaches ran normally but still with some delays on the Southern Region railway.  The fog, which had begun on 5 December, also affected other areas of the south east, with icy roads causing several road accidents. Ambulance and fire staff had to walk ahead of their vehicles to reach those in need.  Heathrow Airport was also severely affected: BOAC (remember them?) reported just two departures and four arrivals: all other flights were diverted to Hurn, near Bournemouth and passengers were taken by train to Waterloo.

The severe weather conditions led to a rise in crime as robbers used the cover of fog to break into houses and shops and attack and steal from Londoners making their way home in the darkness.  The weather even affected cattle brought into Earls Court in preparation for the Smithfield Show.  Farmers spent hours trying to reach the capital and when they finally arrived found many livestock had breathing difficulties. At least one animal died.  It emerged that at least 4,000 people had died as a direct result of the weather.  They were mostly the elderly, the very young and those with respiratory or heart problems.  The main causes of the smog were byproducts of coal-burning that had reached exceptionally high levels, combined with high pressure, near-freezing temperatures and very light winds that meant the smog lingered for several days.

The authorities realised that drastic action was needed and introduced the Clean Air Act in 1956.  It restricted the burning of domestic fuels in urban areas with the introduction of smokeless zones, but heavy fogs continued for some time after the Act while residents and operators switched to new sources of energy.  The Act was revised in 1968 when industries burning coal, gas or other fuels were ordered to use tall chimneys.  In 1974 the first Control of Air Pollution Act introduced regulations on the composition of motor fuels.  By the 1980s and 1990s the increasing use of the motor vehicle led to a new kind of smog caused by the chemical reaction of car pollutants and sunshine.  The 1995 Environment Act introduced new regulations for air pollutants.