Boris Johnson took his seat in the House of Commons just as Maria Miller was asking a question about unwanted dicks. It was probably a coincidence. Miller was talking about the problem of men sending snaps of their privates to women, whereas the prime minister is, this week at least, someone his MPs are not actively repulsed by.

Or not to a very great extent. The benches behind Johnson were certainly not empty, but they weren’t exactly what you would call “packed”, either. A latecomer could have found a seat easily. Indeed, there were a couple of ministers sitting, a little unusually, on the back row, to fill in the gaps. Everyone else had spread out slightly. It was like the stage of male hair loss where long strands can, with a bit of work, be artfully spread to cover the growing bald patch.

Which brings us back to the prime minister. He opened by announcing that more weapons would shortly be arriving in Ukraine. It is definitely the case that the crisis has given him a bit of breathing room from his various self-inflicted troubles. It has given him a chance to make statesmanlike speeches about freedom without having to face the difficult decisions he hates so much.

His MPs are being nicer to him. But those among them who engage in critical thinking might pause to question the implications of the recent reports that the prime minister has been reading documents and attending 8am briefings every day. As during the Salisbury poisoning crisis, when he was Foreign Secretary and we were told how busy he had been phoning his counterparts, the unspoken implication is that in normal times he rocks up to the office at 11 and spends the next hour playing Tetris.

It was a low-wattage exchange with Keir Starmer. Both men wanted to emphasise their unity in the face of Russian aggression, while also scoring a few quick points off the other. Graciousness doesn’t come naturally to Johnson – he had the air of a naughty pupil sitting directly under the gaze of a very angry headmaster – whereas Starmer easily fell into the role of head boy putting aside personal grievance for the good of the school. He would have made a terrifically dull character in an improving 1950s comic: “Calm Kier: Pilot of the Future.”

The Labour leader asked again why the government wasn’t moving faster on sanctions, and why RT (Russia Today), the channel of fantasists, power-mad separatists and Alex Salmond, was still on the air.

Johnson’s replies were that everything had been worked out with allies. “Unity is absolutely vital,” he explained.

“Very shifty” is the prime minister’s resting expression

There are limits to unity, though. Starmer asked about “the flood of foreign money drowning our politics,” meaning Russian donations to the Conservatives, and Johnson snapped back with a gag about Barry Gardiner’s Chinese gold. It got a laugh from his side, but it allowed Starmer to play to his own strength, dignified disappointment. “We have to stand united, and I am not going to be deflected from that,” he replied, full of piety, before coming around for another drive-by shooting. Vladimir Putin, he said, “believes that we are too corrupted to do the right thing, so we must prove him wrong”.

“I do not think,” Johnson replied, “any government could conceivably be doing more to root out corrupt Russian money.” Which is true, in the sense that the Conservatives have managed to get an astonishing amount of it out of Russian wallets and into the party bank account.

The SNP’s Ian Blackford took up the questioning. “We do not raise money from Russian oligarchs,” Johnson replied wearily. Of course not. They are dual-nationality oligarchs. The prime minister hit back, pointing out that Blackford’s “very own Alex Salmond” has a show on RT (apparently it marked the invasion of Ukraine yesterday with a discussion of shortbread – presumably Salmond feels that some national independence movements are more equal than others). That outraged the Nats, who have in recent years declared Salmond an unperson, painting him out of their history as effectively as a discredited member of Stalin’s Politburo. Blackford would later describe it as “quite disgraceful” to link the SNP with Salmond, who simply led the party for 20 years.

Caroline Lucas, for the Greens, had a final go at the Russian interference question, opening by suggesting that the prime minister looked “very shifty” when taking questions on it. Johnson looked about him, aggrieved, and it is only fair to say he was right to do so.

“Very shifty” is, after all, simply the prime minister’s resting expression.