Every McDonald’s in Britain has been warned its owners could face legal action if they fail to take steps to protect staff from sexual abuse.

The equality watchdog has written to all 1,400 branches telling them they must comply with their legal duties, or risk enforcement action, after a BBC investigation uncovered claims of a toxic culture of sexual assault and harassment.

In January, McDonald’s workers told us they still faced sexual harassment more than a year after its chief executive promised to clean up behaviour at the fast-food chain.

McDonald’s said it is “committed” to doing everything it can to ensure a safe working environment for all employees.

It added: “We are confident that the plan we have in place is working.”

The BBC has asked one current McDonald’s employee, who works for a franchise restaurant in southwest Scotland, for his reaction to the letter. He told us he hoped the intervention would lead to ”concrete change” for people like him.

The 19-year-old worker, who we’re calling Alan, told us in January he had been repeatedly subjected to “degrading and humiliating” verbal abuse by his colleagues, and faced “homophobic slurs”.

Alan still works there. He says things are not much different and he wants to “get away” from it.

The letter from the Equality and Human Rights Commission (EHRC), which the BBC has seen, called the allegations in our investigation “troubling” and noted there have been “repeated incidents”.

The vast majority of McDonald’s restaurants are run by franchises, which means individual operators are licensed to run the outlets and employ the staff.

The EHRC said franchises were not covered by the legally binding agreement it entered into with McDonald’s in February 2023 to prevent sexual harassment in its restaurants.

But it said all businesses in Britain, small or large, must comply with the Equality Act.

”It is your duty to ensure that any anti-discrimination and harassment measures you currently have in place are effective, and to take any necessary steps to protect your workers,” the chief executive of the EHRC, John Kirkpatrick, told the restaurants.

The letter sets out the ”reasonable steps” that restaurants could take to prevent sexual harassment.

These include regular risk assessments, ensuring younger and more vulnerable workers are properly safeguarded and ensuring complaints are dealt with sensitively and effectively through an established procedure.

It added that any franchise restaurant that does not comply with its legal duties “may be at risk of enforcement action”.

The EHRC has a range of statutory enforcement powers open to it, including the ability to launch formal investigations.

If an organisation repeatedly refuses to comply, then the watchdog can take it through the courts, where an unlimited fine could be issued.

Liam Byrne, chair of the Business and Trade Select Committee, said the BBC’s investigation of abuse at McDonald’s had “exposed malpractice which was totally and utterly unacceptable”.

He called for the EHRC to explain “why it is only now writing to McDonald’s restaurants about their new duty under the law, to prevent sexual harassment from taking place, when it came into effect nearly six months ago”.

He said it was “especially concerning because the regulator has known about hundreds of allegations of harassment for several years”.

He added: “Parliamentary committees have now twice found the vigour of their enforcement to be disappointing. It’s now vital the public are reassured they’re on top of the problem – and not behind the curve.”

In response, Mr Kirkpatrick said: “We think that generally the best way to get improvement is to work with willing management teams to effect real change.”

He added: “We can impose actions on businesses. If we need to do that, then that is what we will do.”

The BBC first began investigating working conditions at McDonald’s more than two years ago, after the fast-food chain signed its agreement with the EHRC.

In July 2023, we published our initial investigation, which reported claims by workers, some as young as 17, of being groped and harassed almost routinely.

At the time, McDonald’s apologised and set up a new unit to deal with complaints.

Since then, more than 160 people have approached the BBC with allegations while the EHRC has heard 300 reported incidents of harassment.

• A 19-year-old worker said managers would “touch up” other members of staff and some colleagues were scared of going into work. He quit the branch in the Midlands last year.
• A worker said managers inappropriately touched her and customers sexually harassed her. When she raised it, she said she was told to “suck it up”. She quit her job in the West Midlands at the end of 2023.
• A 16-year-old employee based in the West Midlands, who said he was bullied, shouted at and sworn at by managers.
• A 20-year-old who said a male manager sent her topless pictures. She left her McDonald’s branch in the East of England in August.

Earlier this year, we reported that the watchdog plans to intervene again, “in light of serious allegations raised by our work with the company, and the BBC investigation”.

The BBC understands the action plan will involve strengthening the existing measures – which included providing more training and conducting a survey of workers – as well as announcing new steps.

• Listen: McDonald’s – a toxic place for teenagers?

Alistair Macrow, the boss of McDonald’s in the UK, has been summoned twice to Parliament to answer questions in front of MPs since our initial investigation.

In January, he said 29 people had been dismissed over sexual harassment allegations over the past 12 months.

In a statement, a McDonald’s spokesperson said the agreement with the EHRC was signed “with the intention that it continues to evolve to ensure the robust measures we have in place are aligned with any updated guidance”.

It said the letter was sent “to remind our franchisees of their legal obligations to provide a safe, respectful and inclusive workplace for their employees – which is the same legal requirement of all employers,” adding that it “welcomes” any steps that mean it is continuing to make progress in this area.

It said that together with its franchisees, it is committed to doing everything it can to ensure a safe working environment for all employees, with initiatives and measures as part of a cultural action plan.

“These actions include everything from enhanced training programmes and onboarding practices, through to the launch of a new digital speak up channel designed with our and our franchisees’ restaurant crew in mind,” the spokesperson said.

“We are confident that the plan we have in place is working and making a difference to the near 170,000 people currently employed by McDonald’s and our franchisees across McDonald’s in the UK & Ireland today.”

They added that its latest anonymous employee survey showed that 94% of people are aware of ways in which they can speak up.

If you have been affected by any of the issues in this story, information and support is available via the BBC Action Line.

Some of the names in this story have been changed to protect identities.