So many questions off the back of the @PippaCrerar, @matthew_weaver scoop.
One is: did Dominic Cummings seek medical/sci advice before making his trip north - if so, from whom?

There's also the awkward position it puts the PM's official spokesman in.
On 31 March, her told journalists: “I think he’s in touch with No10 but he is at home, he is self-isolating, he has some symptoms.”
At home. Many would assume that to mean his own home.

Of course No.10 are reluctant to go into the detail of the private medical history/private lives of officials. But in a pandemic they know some transparency is needed for public confidence (hence No.10 entering into the discussion at all).

So was the spokesman given incorrect information by Cummings? Or did he know he was in Durham, not London?
Either way, it appears that the statement that Cummings was 'at home' on that day was incorrect.