Ministers are facing fresh calls to agree on a formal definition of harmful gambling so the Mayor of London can impose a ban on betting adverts on public transport.

Sir Sadiq Khan has previously promised to ensure Transport for London (TfL) prohibits the promotion of casinos and gambling websites across the Tube network. However, until the Government draws up a definition, any City Hall policies could be subject to legal challenge.

Last week London Assembly Member Krupesh Hirani, the Labour group’s health spokesman, set up a London-wide action group to tackle gambling harms across the capital’s boroughs using the powers they currently have.

London’s gambling harm rate is almost double the national average, with 5.6 per cent of Londoners affected compared to 2.9 per cent across Great Britain.

Data from the latest Gambling Commission annual report, released on Thursday (October 2), revealed that half of Londoners have participated in gambling over the past 12 months. In the last four weeks alone, 37 per cent of Londoners took part, though this drops to 23 per cent when the lottery is excluded.

“London is on the frontline of the nation’s gambling crisis, and we cannot sit back while communities pay the price,” he told the Local Democracy Reporting Service (LDRS).