This movie was initially banned in certain parts of Wales, as several cinemas were controlled by the miners' unions at that time. It was only when Richard Attenborough personally intervened and screened it for the union leaders that the ban was revoked.
The prominent headline "66,000 Fans See Chelsea and Sigh" on the back of the newspapers refers to a match that took place on September 2, 1959 at Stamford Bridge between Chelsea and Manchester United. Richard Attenborough was a lifelong Chelsea fan and Life Vice President of the club. The inclusion of the report of the 6-3 loss suffered by his team is likely to have been a joke at his expense.
Richard Attenborough (Tom Curtis) and Gerald Sim (Masters) were brothers-in-law in real life. Attenborough was married to Sim's elder sister Sheila Sim from 1945 until his death in 2014.
The major location for this movie was Ipswich's Reavell & Co. Ltd. engineering works which doubled for Martindale Engineering Co. Ltd. Founded in 1898, the firm was internationally renowned for its air and gas compressors. Renamed CompAir Reavell in 1969, it operated from Ranelagh Road until 2005; continuing to run on a smaller scale from Whitehouse Road, it closed completely in 2012.