Dominic Cummings may have committed “a minor breach” of lockdown rules when he drove to Barnard Castle but will face no further action, according to Durham police.

The force issued a statement on the Prime Minister’s top aide’s decision to travel to the county days after lockdown had been imposed, saying it did not consider that by locating himself at his father’s premises he committed an offence.

But it said: “Durham Constabulary have examined the circumstances surrounding the journey to Barnard Castle – including ANPR (automatic number plate recognition), witness evidence and a review of Mr Cummings’ press conference on 25 May 2020 – and have concluded that there might have been a minor breach of the regulations that would have warranted police intervention.

“Durham Constabulary view this as minor because there was no apparent breach of social distancing.

“Had a Durham Constabulary police officer stopped Mr Cummings driving to or from Barnard Castle, the officer would have spoken to him, and, having established the facts, likely advised Mr Cummings to return to the address in Durham, providing advice on the dangers of travelling during the pandemic crisis.

“Had this advice been accepted by Mr Cummings, no enforcement action would have been taken.”

The force added: “In line with Durham Constabulary’s general approach throughout the pandemic, there is no intention to take retrospective action in respect of the Barnard Castle incident since this would amount to treating Mr Cummings differently from other members of the public.”

Responding to the statement, a Number 10 spokesman said: “The Prime Minister has said he believes Mr Cummings behaved reasonably and legally given all the circumstances and he regards this issue as closed.”

But opposition MPs said the fact police believe Mr Cummings may have breached the rules showed that members of the public were right to be outraged at his behaviour.

Labour MP Alex Davies-Jones tweeted: “Durham Police just confirming what we all already knew. Cummings broke the rules whilst we were dutifully obeying for the common good.

“He broke the rules he helped write. Actions have consequences. Your move Prime Minister.”

The police statement came as contact tracers began tracking down people who have come into close contact with coronavirus sufferers, amid reports of major problems with the NHS Test and Trace system.

The service – seen as key to easing lockdown restrictions – has been rolled out across England with the help of 25,000 contact tracers, while an accompanying app is delayed by several weeks.

The Department for Health admitted “some staff initially encountered issues logging on to their systems”, while MPs said they were told the programme would not be operational at a local level until the end of next month.

Baroness Dido Harding, executive chairwoman of NHS Test and Trace, is said to have made the admission in a call with parliamentarians on Thursday morning.

Labour former minister Ben Bradshaw said he asked Lady Harding whether his local authority in Devon – a pilot area for the scheme – was correct in thinking local plans did not need to be in place until the end of next month.

He told the PA news agency: “I simply asked her to clarify the timing on the rollout and I told her what Devon had told me, and she confirmed that, yes, the local operational rollout of this would not happen until the end of June.”

Mr Bradshaw said it was in “complete variance” with Boris Johnson’s pledge to Labour leader Sir Keir Starmer at Prime Minister’s Questions last week that the system will be up and running by June 1.

“It does seem rather worrying to me that the Government keeps launching things or announcing things that either aren’t ready or it cannot deliver on,” Mr Bradshaw said.

Earlier Health Secretary Matt Hancock laughed off claims that he had rushed to introduce the system amid the fierce political row over Mr Cummings’ lockdown breach.

Mr Hancock said people contacted as part of the NHS Test and Trace system must stay at home for 14 days, adding that the “instructions are absolutely clear”.

Asked why people should follow the new self-isolation rules, when even Tory MPs believe Mr Johnson’s most senior aide breached them, Mr Hancock said that it is in “the whole community’s interest”.

“I think that the vast majority of people will understand that it is in everybody’s interest that those who are in higher risk follow the requests from the NHS, these instructions, and it is very important that they do.”

The Scottish Government’s Test and Protect programme also launched on Thursday while Wales’s contact tracing plan is set to go live on Monday. Contact tracing in Northern Ireland is already underway.

In other developments:

– First Minister Nicola Sturgeon announced that Scotland will move to phase one of a four-step plan to ease out of lockdown, with people now allowed to meet a person from another household outside

– The toll of deaths linked to the virus rose to almost 48,000, while at least 189 frontline health and care workers have died after contracting Covid-19

– Up to 4,500 easyJet staff could lose their jobs under plans announced by the airline, while new figures showed the number of passengers arriving in the UK by air fell from around 7.1 million in January to 112,300 in April

Meanwhile, the Government’s plans to ease the lockdown will be confirmed in an official review which Downing Street expects will give the all-clear for schools to begin reopening next week.

Downing Street insiders suggested the easing discussed by Cabinet Office minister Michael Gove is still dependent on scientific advice, as is the use of private gardens for socialising.