Fewer than 0.1 per cent of train passengers stopped for not wearing face coverings have been handed a fine, official figures show.
British Transport Police (BTP) said officers stopped 14,726 people from July 15 to August 15 for failing to comply with the requirement, but issued just 14 fixed penalty notices.
Prime Minister Boris Johnson doubled starting fines for not wearing masks on public transport to £200 this week after scientists warned rule-flouting was at a worrying high.
BTP said fines are used as a "last resort". Travellers are allowed to present Government exemption cards without medical evidence.
Figures released to the BBC under freedom of information laws also showed officers recorded 50,729 "interventions" with passengers not wearing face coverings between 30 July and 8 September, with 7 per cent told to leave the train.
A total of 37 fines were issued between June 15, when the rules came into force, and July 14. Several rows on the railway network between passengers, some involving the police, have gone viral in recent weeks seeing maskless people confronted.
Last month, police said a train passenger was head-butted to the floor and repeatedly punched in the face for asking a fellow passenger to wear a face mask on a service between Slough and Langley in Berkshire.
Politicians have also been caught out. Conservative MP for Devizes, Danny Kruger, apologised for not donning a mask on a train, while DUP MP for East Antrim, Sammy Wilson, said being pictured by a passenger maskless felt “like East Germany under the Stasi”.
A BTP spokesman said: "British Transport Police has been working with rail industry staff since face coverings became mandatory on public transport in England on 15 June 2020 to engage with passengers, explain the importance of preventing the spread of the Covid-19 virus and encouraging people to wear face coverings.
"Enforcement, in the form of fixed penalty notices, has only been used as a last resort."