A “David versus Goliath” legal action gets under way at the high court on Monday as hospitality bosses try to force the UK government to bring forward the reopening date for pubs and restaurants indoors.

A judge will this week consider evidence in the case brought by Sacha Lord, the night-time economy adviser for Greater Manchester and a co-founder of Parklife festival, and Hugh Osmond, the founder of Punch Taverns and a former boss at Pizza Express. The case has been expedited.

Pubs and restaurants in England were allowed to welcome customers again from 12 April after a national lockdown, but only in outdoor areas. Non-essential shops were allowed to reopen on the same day.

The government has set out a timetable aiming to allow hospitality customers indoors in England no earlier than 17 May, although still with restrictions. Other nations of the UK have varying timetables for reopening.

When announcing England’s reopening, Boris Johnson argued that “we can’t be complacent” in reopening the economy, and that caution was necessary, despite the speed of the UK’s vaccination programme. About 32.8 million British adults had received a first dose of a vaccine by Saturday.

But the hospitality bosses bringing the court challenge argue there is no justification or scientific basis for hospitality to be kept closed for five weeks after non-essential retailers in England were allowed to serve customers indoors from 12 April.

Osmond said on Monday the government’s data showed that hospitality was “not responsible” for the spread of infections, although he acknowledged that the action would have to beat a “high bar” in proving that the government’s actions were not reasonable.

“This is something of a David versus Goliath battle,” he said. “We are reassured that David won in that instance.”

“At the start of this pandemic there was a totally understandable assumption that hospitality venues might be responsible for the spread of infections,” he told BBC Radio 4. “The vision of drunken people in crowded pubs is an easy and obvious target that people understand.”

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Osmond argued that analysis of the government’s data showed that hospitality was not responsible for a rise in infections. “This data definitively shows that hospitality was not the major source of infections,” he said.

A government spokesperson, who declined to comment directly on the legal action, said: “We have been clear that we want this lockdown to be the last and to achieve that our approach to cautiously easing restrictions is informed by the best available science and the latest clinical evidence.

“The government has supported the hospitality sector throughout this global pandemic, including our new £5bn restart grant scheme, extending the furlough scheme and the VAT cut, and providing 750,000 businesses in hospitality and other sectors with business rates relief.”