Borough Market has used an obscure pre-Victorian law to make wearing masks outside at its market legally enforceable.
The by-law, dating back to 1829, means the market is the first outdoor venue to make wearing a mask legally enforceable, it says.
Offenders at the busy market now face a £50 fine if they do not wear a mask despite being asked repeatedly by security staff to do so.
Adrian Bunnis, Chair of the market’s trustees, said: “We have encouraged the wearing of face masks since the first lockdown.
“We have now decided to enforce it through our by-laws in the knowledge that the vast majority of our customers will support this.
“With London being the epicentre of the new Coronavirus variant, we feel we have a duty to the community to do this so they can shop in confidence.”
The move also means that shoppers will be prohibited from eating food and drink in the market area, as it would involve removing a mask.
Access to the market will be restricted, with a one-way-system in operation.
Security guards will carry out checks at the access points and help ensure social distancing is place, say market officials.
The power is given to the trustees under the Borough Market (Southwark) Act 1829, which sets out market by-laws.
The news comes after the market’s managing director, Darren Henaghan, said traders were stockpiling cheeses over Brexit.