Cummings got it wrong in the Rose garden.
He got it badly wrong and Boris will be damaged the more he tries to hold on to the man.
There may still be time to claw this one back but the route is very simple. The explanation as he gave it is arrogant and self-serving. What he should have said is this, “I am sorry. I have let down Boris and I have let down the country. I know I fouled up but there are important jobs to be done and I would like to get on with them if the PM will let me.” If he needed to justify himself further, he could have added his chronology with the following rider, “For the record, I felt, at the time, that what I did was within the letter of the law that I helped to draft. But I must be held to a higher standard and I failed.”
In this context, he would have been allowed, even encouraged to stay, to make amends.
The only reason to appear on TV was to make him likeable. So he failed.
More than that, he exposed much of the Government machinery to failure in their attempt to support him.
There were a number of attempts to bury the story, some more outrageous than others. All failed, but his cack-handed appearance in the rose garden was intolerable. It also flies in the face of the special advisor code which argues against people like Cummings making public statements in this way.
The only reason ever for a politician to appear on tv is to put a face to a story, to humanise an issue. TV supports emotion or action. Therefore, any “explanation”, in that context, comes across as deceptive and weaselly, no matter how true and valuable it may actually be. Nobody wants to listen for an hour to an explanation, and particularly not to a man of privilege offering an “explanation”. TV is not a courtroom. That is precisely what we were given. The only emotion we saw came from the reporters. the only action was to drink water. Tiresome.
It gets worse. The more useless Cummings becomes because of his lockdown run, the more Boris has to assume the mantle of earnestness. He is better being shambolic, and charming but he cannot play the shambles when all around him is crumbling. What an unqualified mess this special advisor has created.
animate-tim.com 
Beautifully put.