Dominic Cummings’ alleged lockdown breaches have provoked a junior minister to resign from Government amid continued anger at Boris Johnson’s chief adviser.

Douglas Ross, the parliamentary under-secretary of state for Scotland, said on Tuesday that he was quitting after hearing Mr Cummings’ efforts to defend his trip from London to Durham.

Mr Ross said he could not “in good faith” tell his constituents who could not care for sick relatives or say goodbye to dying ones while obeying lockdown rules that Mr Cummings acted appropriately.

The first resignation over the allegations rocking the Government came as Cabinet Office Minister Michael Gove sought to defend his longstanding ally as having acted “entirely reasonable” and within the law.

Mr Ross said that “while the intentions may have been well-meaning”, Mr Cummings’ interpretation of the rules was “not shared by the vast majority of people”.

“I have constituents who didn’t get to say goodbye to loved ones; families who could not mourn together; people who didn’t visit sick relatives because they followed the guidance of the Government,” the Tory MP for Moray wrote.

“I cannot in good faith tell them they were all wrong and one senior adviser to the Government was right.”

A No 10 spokesman said Mr Johnson “regrets” Mr Ross’s resignation, while Conservative former minister Tim Loughton said the “brave decision” should “not be readily dismissed”.

The resignation came amid continued concerns over how the Prime Minister’s defence of Mr Cummings will affect the public, police and health workers during the pandemic.

In an extraordinary press conference for an adviser, Mr Cummings argued that his journey to Durham in March was justified as he sought to protect his family’s health.

But many questions remained unanswered, including over his subsequent drive to Barnard Castle which he said was to test his eyesight after it was affected by Covid-19.

Mr Gove said the journey, some 25 miles from where the aide was isolating, was “completely appropriate” because he was “preparing to return to work” by checking he was safe to drive the long trip back to London.

Told that the reason “preparing to return to work” did not appear under the regulations, Mr Gove replied: “No, but the key thing is Dominic is a key worker and being in a position to return to work is a sensible thing.”

“It’d have been entirely within his right to return to work that day on the basis of the advice he had been given, that’s my understanding, so that drive was completely appropriate,” he added, to BBC Radio 4’s Today programme.

Former Greater Manchester Police chief constable Sir Peter Fahy said officers had become “frustrated” by the fiasco, which may hinder policing with the rules “now very confused”.

“Clearly, number one, that’s ill-advised as a means of testing your eyesight as to whether you’re fit to drive, but again it’s hard to see – unless there’s some justification that that was to take daily exercise – how that was justified,” he told Today.

And, asked if it was a criminal offence, Sir Peter replied: “It certainly appears to be against the Highway Code – it’s not the way to test your eyesight, and put potentially other people in danger.”

He also said “it may well be that absolutely he’d have been turned back” by officers if they stopped him during the drive north from London in March.

NHS Confederation chief executive Niall Dickson said: “Because of the way this story has unfolded, there is certainly concern among our members, health leaders, that it could damage staff and public confidence in official guidance.

“So I think there is concern that this has been a distraction and that it’s not been helpful, and the fear is that it has made people on the front line frustrated and fearful.”

Professor Stephen Reicher, who advises the Government on human behaviour during disease outbreaks, said the PM is risking undermining community spirit by backing Mr Cummings.

“Now, thank God, the public at large didn’t take that attitude, the public at large, as I say, made those major sacrifices, but it threatens to undermine that sense of community if a figure as prominent as Dominic Cummings and if the Prime Minister himself starts undermining that ‘we’ message and starts talking about ‘I’,” he told Sky News.

The political storm created by Mr Cummings’ press conference on Monday overshadowed Mr Johnson’s announcement that all shops in England will be able to open next month if they can protect shoppers and workers.

The adviser told reporters in No 10’s garden that his wife, journalist Mary Wakefield, fell ill on March 27 – leading him to swiftly leave Downing Street for home.

He said she felt better after a couple of hours and he returned to Downing Street before they later discussed the situation further, including the fact that many in No 10 had developed Covid-19 symptoms.

Mr Cummings said he was worried that if they both fell ill, there was “nobody in London we could reasonably ask to look after our child and expose themselves to Covid”.

He declined to apologise and said he did not regret his actions when he outlined how he drove from his home in London to County Durham during the lockdown.

Simon Jupp became the latest Tory MP to suggest that Mr Cummings should consider his position, saying he has felt “anger, disappointment and frustration” during the “deeply unhelpful distraction”.

William Wragg, Tory chairman of the Commons Public Administration and Constitutional Affairs Committee, said it was “humiliating” to see ministers defending Mr Cummings.

“We cannot throw away valuable public and political goodwill any longer,” he said.

Veteran Conservative MP Sir Roger Gale said the backbench 1922 Committee should tell Mr Johnson that Mr Cummings has to go.

In other developments:

– The PM said the Government would set out a formal assessment of the five tests it set for adjusting the lockdown later this week as part of the three-weekly review on Thursday

– The Office for National Statistics said there were 3,810 coronavirus-related deaths in England and Wales registered in the week ending May 15, the lowest weekly number in the last six weeks.

– The number of excess deaths in the UK since the coronavirus outbreak approached 60,000.

– Nazanin Zaghari-Ratcliffe’s husband said she could receive a decision on her clemency on Wednesday in Iran, where she she was freed from prison on March 17 as a response to the pandemic.