Tuesday was self-justification day in Parliament. There was a little queue of people who wanted to tell us that they were doing a good job in difficult circumstances.

First up was Dido Harding, in charge of the government’s Test and trace programme, which readers may recall is the thing that is going to stop Britain going into lockdown this winter. Its success on this score could charitably be described as “mixed”.

Harding is one of those people who populate the top of British corporate and public life: assured, plausible, Field Marshal descendant, sincere, very slightly spiky when asked critical questions. A little bland, but in a reassuring way. If she phoned you up – ideally only once – and said you had Covid, you’d believe her.

When these people are appointed, often in irregular ways, we’re told that no one matches their brilliance. But when things go wrong, we’re told no one could have done anything differently. Which, admittedly, is a kind of genius.

Harding has a plausible CV: Tesco, Sainsbury’s. Was she behind the success of these supermarkets? Who knows? Much is made of the data leak when she was CEO of TalkTalk, but as a former customer I’m more inclined to focus on the way that the broadband couldn’t cope if more than two people in the street wanted to watch a film at the same time. Was that Harding’s fault? Hard to say.

In another life, she might have joined the civil service from Oxford, and risen through the Department of Health to the point where she was senior enough to be pushed aside by Matt Hancock in the summer, to be replaced by a dynamic outsider, Admiral of the Fleet granddaughter, from the private sector, Hido Darding.

In this reality, the question is whether she is doing a great job in the face of terrible adversity, or just a terribly under-advertised job. The trouble is that it’s very hard to tell. Jeremy Hunt, chairman of the Health Committee, tried to find out, asking why her outfit hadn’t managed to stop Covid spreading. It couldn’t be a “silver bullet,” Harding replied, sadly, sincerely.

She was asked whether it wouldn’t have been better if the Test and Trace service were focused more on local teams, better placed to tackle outbreaks in communities that they know. Harding swerved this. She was leading a “team of teams”, and every team in her team of teams was vital and precious. It was mistaken to suggest that there was too much emphasis on the national side of the operation.

It was all so reasonable. Would someone else be doing better? Maybe, just maybe, someone else would have questioned whether schools going back in September might increase demand for testing. “With the benefit of hindsight, could we have built testing capacity faster?” Harding explained. “I’m not sure anyone could.”

Having talked about hindsight quite a lot, Harding was asked whether there might be other peaks in demand. She was doing the best she could, she explained, “armed only with my crystal ball.” Perhaps she should put the ball down and consult a calendar of term dates instead, but everyone was too polite to say so.

Over in the Commons chamber, a little later, Hancock himself was discussing the Covid vaccine news. Most of Hancock’s virus statements have involved him defending himself over things that aren’t going to plan. On Tuesday afternoon, his manner was that of the class nerd who unexpectedly snogged someone at a party on Saturday night.

“The virus remains a powerful adversary, but we’re marshalling the forces of science and human ingenuity,” he swaggered, putting on his best Churchill. “I have no doubt that in time we will prevail.”

Sir Desmond Swayne, one of Conservatives’ lockdown-doubters, tried to prick the Health Secretary’s bubble. Swayne has always had a slightly eccentric air, not helped by his double-breasted suit and blue-shirt-with-white-collar stylings. If Swayne told you the time of day, you’d quietly seek a second opinion. The graphs used to justify lockdown were wrong, he told Hancock. We could have carried on as before, and “the NHS would have coped, wouldn’t it?”

Boris Johnson is always careful with these questions, seeming to sense the troubles that may follow once people start disabusing Tory MPs of cherished beliefs. But Class Stud Hancock was having none of this. He rose and replied to Swayne with a single word: “No.” Take that, sceptics!

Hancock was generous with praise for everyone: NHS staff, vaccine scientists, testing workers. He’s mastered the art of making it very clear that he is simply the messenger, bringing news of other people’s hard work, while somehow managing to convey the idea he might deserve a bit more credit than he’s letting on. Perhaps he suggested which bit of the virus code the boffins should use for the vaccine. He’ll never tell, and we’ll never know.

So, is the vaccine going to save us? That had been the question that MPs had asked Oxford’s Professor Sir John Bell. He was optimistic, sort of. The vaccine, and the others following in its wake, would do the job. “That’s provided they don’t screw up the distribution,” he added. “Provided they don’t screw that up, it’ll all be fine.”

Screw up? This lot? The people who managed to conceal a message of congratulation to Donald Trump in a message of congratulation to Joe Biden? But not to worry. Even if they do, they’ll be along quickly enough afterwards to explain that no one else could have done better.