Llanfairfach was a small town located in Wales, about an hour away from the city of Newport. It was home to both a coal mine, the main source of its economy, and a commune named Wholeweal. (TV: The Green Death) It was the hometown of Private Gwynfor Evans. (PROSE: The Feast of Evans)
On 24 December 1969, Gwynfor Evans and Samson Ware dealt with slug-like creatures which attempted to create a combat machine using parts stolen from the Christmas presents. (PROSE: The Feast of Evans)
In 1973, (HOMEVID: Global Conspiracy?) the National Coal Board closed the coal mine, causing the loss of many jobs. However, Global Chemicals later opened an oil refinery there, promising prosperity for the town. Clifford Jones opposed it over environmental concerns. The Third Doctor and Jo Grant went to Llanfairfach to investigate the mysterious death of Hughes, whose body had been found glowing green. They discovered that Global Chemicals was dumping lethal toxic waste into the abandoned mine, which also had the side-effect of creating giant maggots. The refinery was shut down.
Luckily, thanks to string-pulling by Jo Grant, the United Nations decided to fund the Wholeweal commune as a research facility. The money and extra work brought needed jobs to the town. (TV: The Green Death)
In 2003, Gordon Williams died after touching toxic waste leftover from Global Chemicals. After reading about the incident in the Newport Echo, investigative reporter Terry Scanlon came to Llanfairfach and interviewed several of its residents. (HOMEVID: Global Conspiracy?)
By 2019 a company called Llanfairfach Pharmaceuticals made a brand of suntan lotion, which not only contained green maggots, but also had some strange mind-altering properties. (PROSE: The Llanfairfach Rebellion)
With one exception, Llanfairfach is never pronounced correctly in The Green Death. The correct pronunciation is given by Dave Griffiths whilst telephoning the National Coal Board in episode one.