By Sarah Bloch-Budzier BBC News
Boris Johnson's top adviser has faced calls to resign after travelling 260 miles during lockdown in order to get childcare cover.
Downing Street says Dominic Cummings' actions were in line with coronavirus guidelines - so what exactly are the rules and how have they been applied?
Government advice for households where one or more members have coronavirus symptoms is simple: stay at home.
But official guidance published in March does acknowledge that it is not always straightforward when children are involved.
The document says "it is very important that individuals with symptoms that may be due to coronavirus and their household members stay at home", and outlines ways to pass the time and obtain food and medicine.
But it also says that: "If you have children, keep following this advice to the best of your ability, however, we are aware that not all these measures will be possible."
The guidance has been in place on the government website since 12 March, before lockdown was imposed.
The day after lockdown began, 24 March, the deputy chief medical officer for England, Dr Jenny Harries, clarified who could look after a child if both parents or carers were incapacitated.
She said: "Clearly if you have adults who are unable to look after a small child, that is an exceptional circumstance. And if the individuals do not have access to care support - formal care support - or to family, they will be able to work through their local authority hubs."
As Dr Harries pointed out during Saturday's Downing Street press conference, any of the government lockdown guidance can be overruled by safeguarding concerns, or prevention of harm, and cited an elderly person with no supply of medication or a child with both parents too unwell to provide medical care as examples.
She also said that "risk to life" would be a valid reason to break lockdown rules.
When Dominic Cummings decided to travel from London to Durham to stay near his relatives for support, only his wife was displaying coronavirus symptoms, so he could have cared for their child himself.
But Transport Secretary Grant Shapps said at Saturday's briefing that the welfare of a four-year-old child was the main thing - and that Mr Cummings' actions had prevented the child from being without any support, should things have become worse.
Mr Shapps said that government guidance was to keep following the advice to best of your ability.
He acknowledged that not all measures would be possible depending on the circumstances of each family.
He said that in this case, Mr Cummings was worried about his ability to care for his child and that another location with help from the younger members of his extended family was a better place for him to settle and stay for the duration of his illness.
The government stressed on Saturday that there was no longer any restriction on how far asymptomatic people can drive - for example to take exercise - but that those who had symptoms should remove themselves from the wider population.
It is worth noting that Mr Cummings was able to stay in a separate property near to his parents and sister and so did not have to mix households - something not everyone would have the means to do.
But as Grant Shapps said at the Downing Street daily briefing: "In moments of crisis we seek our family around us."
That is something that many people who have been separated from loved ones through bereavement or other difficulties in recent months will know all too well.