Britain’s biggest white-collar employers have sent staff home after the government tightened its coronavirus guidance, but some companies have told workers they can continue to come to the office if required for their mental health. Although the government instruction that people in England should work from home where possible from Monday is advice and not legally mandatory, organisations across the country are switching to home working where possible. Amid growing concern about the psychological impact of nearly two years of restrictions, employers appear to be taking a more flexible approach than in the early months of 2020. The accountancy firm PwC and the law firm Slaughter and May are among the large businesses that will allow workers to continue to travel to the office if they have mental health needs, or if they are unable to work from home, as well as for business-critical reasons. Boris Johnson introduced the new tighter “plan B” Covid restrictions for England on Wednesday as his government faced a barrage of criticism over Christmas parties alleged to have taken place in 2020. The devolved administrations in Scotland and Northern Ireland had already asked people to work from home. Wales has not so far strengthened its guidance. Most people in the UK – ranging from shop staff to factory workers – are not able to work from home. However, some studies have found that many people who have been forced to work alone for long periods have reported increasing problems such as loneliness and mental distress. The change in guidance may cause some disruption for some large office-based employers including auditors, who tend to have a busy end-of-year period while preparing for the company reporting season. KPMG, another large accountant, said it had told workers that only business-critical meetings should take place in person, and only at “Covid-secure KPMG offices or client sites”. Offices at its rival Deloitte will also remain open if people cannot work from home – albeit with the requirement for masks and lateral flow tests. Kevin Ellis, the boss of PwC, said on Wednesday: “There’s no denying this will be a challenge for some sectors. The majority of our people had returned to the office two to three days a week. It’s the busy season for audit and there’s also lots of deal activity that benefits from some in-person meetings.” Some employers have been forced to retreat from tentative steps made to increase the number of staff working in the office before the Omicron variant was identified. The insurer Aviva had adopted a hybrid working system, allowing staff to split their time between home and the office, albeit with extra precautions such as a lateral flow test every day before commuting in. It has now asked all staff to work from home if possible. The UK’s financial watchdog, the Financial Conduct Authority (FCA), had only just begun its hybrid working trial at its offices in Stratford, east London, requiring staff to spend 20% of their time in the office. Prior to December, employees were able to work from home unless there was a particular need for them to attend the office. That has now changed, and all employees will work from home unless they have a specific or agreed requirement to come to the office. The rise of the Omicron variant had already prompted some companies to take action before the government advice changed. The wealth management firm Brewin Dolphin had told its 2,000 UK staff that “unless it is necessary for work to be undertaken in the office” staff can work from home until at least 7 January.