Those two 'ifs', Nigel. That he went to Durham and back is indisputable. The press reports on this are correct. As to if he was unsure he should have got advice. He is wrong either way. If he was sure he should not have gone. If wasn't sure and had got medical advice they would have told him not to go.

The first 'If' was about the accuracy of the press reports (plural), not whether he went to Durham, which was not denied. There were multiple press reports. Not all were substantiated.
As to advice, the comment was about what he should have done if he was unsure. By his own description, he knew what the restrictions were, and believed he was covered by them. In that case, he was not unsure, and no further reference to a 'higher authority' was required.
The response to Raggytash's email is carefully worded. It is a shame others aren't worded so carefully.

And, before anyone asks, I also think Cummings should have gone by now, either by his own decision, or by Boris'.