Sir Patrick Vallance publicly warned over use of ‘reasonable worst-case scenario’ coronavirus data

Chief scientific adviser expresses ‘regret’ if handling of data caused public concern

Sir Patrick Vallance, the government’s chief scientific adviser, has been publicly warned by the official statistics watchdog over the use of data to justify the latest coronavirus lockdown.

The Office for Statistics Regulation (OSR) criticised the failure of the government to release the data and assumptions behind a controversial projection that there could be 4,000 deaths a day unless action was taken.

The modelling – which was one of a series of projections highlighted during Saturday's Downing Street press conference to announce the latest restrictions for England – was widely criticised by Tory MPs as alarmist.

Giving evidence to the Commons Science and Technology Committee on Tuesday, Sir Patrick expressed “regret” if the way the “reasonable worst-case scenario” was presented had caused public concern.

However, the OSR disclosed that the chair of the UK Statistics Authority, Sir David Norgrove, had since spoken to the chief scientist directly, to express concern about the way data had been used during the pandemic.

In a letter to Sir Patrick, the OSR director general for regulation, Ed Humpherson, warned there was a danger the public could be “confused” and that confidence in official figures would be undermined.

“We welcome the range of data that has been published and we recognise that those producing the data and advising government face significant pressures,” he wrote.

“However, the use of data has not always been supported by transparent information being provided in a timely manner. As a result, there is potential to confuse the public and undermine confidence in the statistics.”

In a separate blog post, the OSR said when modelling was publicly referred to by ministers and officials, there was an “expectation” that associated information, including key assumptions, was also made available in an “accessible and clear way”.

“In the press conference on 31 October this was not the case,” it said.

“The prime minister referred to the reasonable worst-case scenario – a model set up to support operational planning. However, the data and assumptions for this model had not been shared transparently.”

Boris Johnson however defended the government's use of data in making the case for the lockdown.

He told a No 10 press conference on Thursday: “We try to make things as clear as we possibly can.”

The prime minister acknowledged that the “projections vary widely” and that there was also a “political judgment” to be made, taking into account the economic consequences, when imposing new controls.

“It's very, very tough to make exactly the right call,” he said.

The prime minister added that some of the facts were “irrefutable” such as the number of deaths and people in hospital.

“I can't quarrel with those data, we have to act on those data and collectively, that's what we're going to do,” he said.

A government spokesperson said: “Our approach throughout this unprecedented global pandemic has been to increase transparency around the government’s response to coronavirus.

“We continue to work hard to improve the data we publish where necessary, and our efforts and statistical reporting has been recognised by the UK Statistics Authority, which said ‘there is a continual process of improvement’.”

Additional reporting by PA