Dominic Cummins drove with his wife who was already symptomatic with Covid-19 from their London home to his parents’ home in Durham, a distance of 270 miles. While there the family went for a walk in a wood 30 miles from his parents’ home.
This much is admitted. Not much else is and he and the government are not answering questions such as whether the party (carrying the virus) stopped anywhere on the way or, indeed, how they travelled .
It isn’t 100% clear whether Cummins was symptomatic when this journey began. On the one hand they need him to be because this bolsters the story about how the parents were motivated to try and find childcare for their child. On the other hand this would make the matter worse as moving doing anything other than going home and self-isolating when infected would break the guidance to stay at home if you have symptoms.  This is why this area of the story is so opaque. The guidance  is also clear that if one member of the household falls ills then others should isolate at home with them – except they are allowed out if essential to buy food.
Cummins broke 2 or 3 rules. Firstly; when his wife was ill she should have stayed in their home (which is in London, not Durham) and he should have stayed with her. They should not have gone anywhere. He broke this rule. If he himself was symptomatic he broke the rule as it pertains to him. In general during the lockdown people are not allowed to move households.  Finally; at the time they took their stroll in a beauty spot 30 miles from where they were then resident police forces were penalising people for doing just this; driving long distances to visit beauty spots. These last two points have the force of law. 
Cummins broke the guidance and he broke the law.
In protecting him as he as done the Prime Minister – with a patently not true claim that Cummins did not break the law and that he acted with “integrity” – does not so much broadcast the message that there is “one law for us and another for the people” but broadcasts the message “we, the rulers, don’t care about the law; the law has no meaning; if you can get away with it, why not?”. He is embedding lawlessness and lying right at the very heart of government. Odd, considering he is the Prime Minister.