Downing Street has confirmed a loophole exists allowing people from different households to meet in restaurants in tiers two and three if they are working.
A spokesperson today said: 'There is a specific exemption which says that people from different households can gather in indoor settings that are open for work purposes.'
But they stressed this is meant for freelancers and not a green light for pub meals with friends under the guise as boozy working lunches.
Number 10 said: 'The reason that is there is that there are some people such as the self-employed and freelancers who may not have a workplace to conduct business meeting that need to take place face-to-face.
'We would encourage people to use alternatives to work meetings where possible.'
Yet it was suggested this is simply guidance and non-freelancers who take advantage of the loophole are not liable for fines.
The hospitality trade body today branded the rules a 'grey area' and said further clarity was needed.
The loophole could pave the way for a surge in 'working lunches' among the 28 million people living under tighter restrictions which bans two households mixing indoors.
Up to 30 people from different households may meet indoors for work, as long as the place they are meeting is Covid-secure, according to Government guidance.
The apparent loophole caused a stir on Twitter today, with some users planning a 'working lunch of eight pints at 9pm' and a '9am meeting' in a Wetherspoon pub - while on a more serious note it also raises the hopes of hospitality chiefs.
A No10 spokesman confirmed that while current rules advise people to limit their social contact and work from home 'where possible', people are permitted to meet indoors for work purposes 'in high or very high areas'.
Restaurateurs and landlords are now desperately calling for much-needed clarity over the loophole, which they hope could revive their business.
Officials insist the curbs suppress Covid-19, but the restrictions are being increasingly criticised by Tory hawks who view them as economy-wrecking.
The Department for Business, Energy and Industrial Strategy said that office workers should continue working from home, and that people should not bee attending restaurants or pubs with those outside their household in tier two areas.
In tier three areas, pubs are closed other than those which serve 'substantial meals'.
UKHopsitality chief Kate Nicholls, who had warned London Mayor Sadiq Khan that tier two restrictions in the capital would lead to 250,000 job losses, called the loophole 'a real grey area'.
She told The Daily Telegraph: 'The Government has given an exemption for business meetings up to 30 or meetings or gatherings that are deemed necessary for work purposes, but it's provided no guidance on where those meetings can take place.
'We're asking for urgent clarification because in central London, if the working lunch is gone, there's no trade.'
Stools up on a table top at a cocktail bar in London's Covent Garden last Saturday
Drinkers outside a pub in Soho, London, on Saturday after Tier 2 restrictions were imposed
People pass empty tables outside a restaurant in London's Covent Garden on Saturday
Ranalad Macdonald, managing director of London restaurant group Boisdale warned last week that he might have to shut if work meetings were banned.
Top chef Yotam Ottolenghi joins hospitality workers protesting against 'devastating' Tier 2 London lockdown they say will 'kill' restaurants and bars
Yotam Ottolenghi in London yesterday
Top chef Yotam Ottolenghi has joined hospitality workers in a noisy demonstration against 'devastating' tier two coronavirus restrictions in central London.
Around 200 workers, from farmers to chefs and events organisers, filled Parliament Square with a metallic uproar by banging metal cooking utensils on Monday morning.
From midnight on Friday, London was thrown into tier two lockdown meaning individuals from different households are banned from mixing indoors - even in hospitality venues - with outdoor socially distanced mingling permitted for groups of up to six.
The shock restrictions, which were announced less than 48 hours earlier, mean 200,000 potential job losses for hospitality workers in central London alone.
Critics have warned the lockdown puts in force a 'maximum squeeze on revenue and no support' for struggling businesses and employees.
Almost a third of restaurants and pubs in England are set to be affected by the tougher tier curbs - more than 8,500 venues and 5,000 pubs.
He told City AM: 'All our lunch trade is business… We will go from making a loss whilst trading to haemorrhaging money.'
It comes after experts warned that the Covid-19 catastrophe is creating 'ghost towns' across Britain and threatens to wipe out more than a million jobs.
A record 11,120 household-name retail outlets and around 125,000 store jobs were lost after the first lockdown supercharged a move away from high streets.
However, this is just the tip of the iceberg, with fears the job loss total at shops, pubs and restaurants could soar as new lockdowns are rolled out this winter.
Hospitality industry leaders say that as many as 750,000 jobs could go in their sector alone by early next year – and a total of 255,000 retail jobs could be lost by the end of 2020.
Kay Neufeld, of the Centre for Economics and Business Research, said it was 'plausible' that there could be more than one million job losses in the retail and hospitality sectors alone.
The Social Market Foundation, an independent think-tank, said: 'Reduced demand for office space, and a seemingly inevitable decline of traditional retail, risk creating ghost town and city centres.'
The British Chambers of Commerce is warning of 'hundreds of thousands of job losses' amid the closure of the furlough scheme, which currently supports more than two million workers, this month.
More than one in four of the UK's 39,700 pubs may not survive the pandemic, according to the British Beer and Pub Association.
Greene King plans to close 79 pubs, putting 800 jobs at risk, while Young's, Wetherspoons, Fuller's and City Pub Company have all said they will cut several hundred staff.
Nick Mackenzie, of Greene King, said: 'Pubs are becoming increasingly unviable.' He added: 'This means extending furlough to cover all hospitality venues hit by restrictions, not just those forced to close, extending the VAT cut and business rates holiday and cutting beer duty.'
Pub and restaurant operator Mitchells & Butlers, which owns Harvester and All Bar One, said that the industry was facing 'exceptionally challenging and uncertain circumstances'.
They added: 'We strongly urge the Government to step up the level of support it is offering to an industry which has been repeatedly singled out and taken the full brunt of restrictions.'