The prime minister’s chief adviser Dominic Cummings has said he does not “regret” driving 260 miles from London during the coronavirus lockdown.
He revealed he had not told Boris Johnson when he decided to take his family to County Durham after his wife developed Covid-19 symptoms.
Mr Cummings said he believed he was acting “reasonably” and within the law.
Speaking in the Downing Street garden he added that he had not considered resigning over the issue.
But Mr Cummings – whose behaviour has dominated the headlines during the last few days – said he should have made a statement on his journey on 27 March to County Durham earlier.
“I don’t think I am so different and that is one rule for me and one rule for other people,” he said in a statement.
He said: “I do not regret what I did,” but added that “reasonable people may well disagree”.
Mr Cummings’s statement comes as the UK government says the number of deaths among people who have tested positive for coronavirus – in all settings – has has risen by 121 to 36,914.
Mr Johnson is expected to give his reaction to his adviser’s comments when the regular Downing Street press conference takes place at 19:00 BST.
Many people, including Conservative MPs, have called for Mr Cummings’s dismissal, despite the prime minister giving a statement earlier on Sunday in support of his chief adviser.
In his statement, Mr Cummings revealed that his four-year-old son had been taken to hospital with a “bad fever”, while the family were in Durham but had tested negative for coronavirus.
He also confirmed that he had driven about 30 miles from Durham to Barnard Castle on Easter Sunday – a time when the government was warning people not to visit tourist spots.
But he said he had done so to “test his eyesight”, which he had been concerned about during his own recovery from the virus, before embarking on the long drive back to London after completing his self-isolation.
“I wasn’t sightseeing, I didn’t go to the castle,” he told reporters when he was repeatedly pressed on the trip during an hour long defence of his actions.
Mr Cummings said his family home in London had been the target of protests – and he did not have access to childcare in London if he and his wife both fell ill.
His sister and his nieces, who lived in Durham, had offered to look after his son if necessary and he took the decision to drive there.
He insisted they did not stop during the 260-mile journey to Durham but may have stopped on their return to London – on 13 April – to get petrol.
He said he isolated in a cottage on his father’s farm 50 metres from his parents’ home but did not have any contact with his parents, who are in their 70s, other than shouted conversations.
And he believed he had kept to government guidelines, which tell people who develop symptoms to stay in their homes, because they also allow for some leeway in “extreme” circumstances.
He said he was not surprised that lots of people were angry about his actions but “it was a complicated, tricky situation”.
By BBC political correspondent Jonathan Blake
For most people outside of government, and for some inside it, this is the most we’ve ever seen and heard of Dominic Cummings.
He cuts an unassuming future; sitting behind a fold-up table wearing an open shirt speaking calmly and relatively quietly.
There was less bravado than you mighty expect – in recent days we saw Mr Cummings waving away photographers outside his home and telling reporters “it’s not about what you guys think”.
He mentioned writing last year about the dangers of coronaviruses, perhaps an example of his apparent enthusiasm for “super forecasting” and predicting future events.
There was criticism of the media and what he claimed to be inaccurate reporting of his actions.
But time and again, in the face of sustained questioning, he said he didn’t regret taking his wife and child to Durham during lockdown, or taking them on a test-drive before he returned to London.
Whether he has helped or hindered his own standing and that of the government’s will depend on the judgement of individuals.
And whether he keeps his job? As Mr Cummings himself said, “It’s up to the prime minister”.