The next few days will be a big test for the chancellor. Rishi Sunak is the leader of the group of ministers in cabinet who want to keep Britain open, against those, led by Matt Hancock and Michael Gove, who want to shut it down. So far, Boris Johnson has brokered a compromise between them, but it is a halfway house built very much on Sunak’s side of the line.

The key decision was made four weeks ago, when the Scientific Advisory Group for Emergencies (Sage), urged more restrictions and presented a number of options. The most dramatic was the idea of a circuit breaker, a short national lockdown to try to halt the spread of the virus and postpone its resurgence.

Johnson resisted that policy and went for only one option on the list, the softest, namely re-reversing the government’s advice from “go to work if you can” to “work from home if you can”. That was a big victory for Sunak, although we didn’t know about it until the Sage minutes were published on Monday.

The chancellor spelt out his argument when he presented his Winter Economic Plan three days after the Sage meeting. “It would be dishonest to say there is now some risk-free solution,” he told the Commons. He came as close as he could to saying that it would cost too much in lost jobs and deaths from other causes to try to suppress the virus further. We must “learn to live” with the virus, he said, “and live without fear”.

However, the argument continued to rage in government, with a statistics disaster adding to the sense of confusion when information about thousands of cases went missing. At one point, Johnson agreed to a circuit breaker, only to have his mind changed by another forceful intervention by Sunak. Some sources suggest that the chancellor threatened to resign, but I am told that is not the case.

Sunak is in a strong position, by virtue of having the power of the Treasury at his back (it seems a long time ago that his appointment was seen as a takeover of the Treasury by No 10), and of being the most popular minister in the government. For him to give that up by resigning makes no sense. Where is Johnson’s great personal friend Sajid Javid now?

My understanding is that Sunak prevailed on the prime minister by force of argument rather than by threats. This prompted some rude comments at the time from ministers on the losing side about Johnson’s malleability, with one suggesting that the prime minister is a leader of fixed opinions – opinions fixed by the last person to whom he has spoken.

In any case, as the number of coronavirus cases continued to rise, the argument continued to be fought. Each time, although the prime minister appeared to be moving towards the Hancock-Gove position, he actually did the minimum possible. The 10pm closing time for pubs – although it provoked outrage among libertarian Conservative MPs – was a limited measure, the alternative to closing them down altogether. 

The three-tier regime of graded restrictions was similarly the least Johnson could do while keeping Chris Whitty, the chief medical officer, and Sir Patrick Vallance, the chief scientific adviser, on board. Everyone noticed that Professor Whitty, standing next to the prime minister when the three tiers were announced, in effect said that even tier 3 wouldn’t be enough on its own to control the virus.

That is why Keir Starmer’s big decision on Tuesday to argue for a circuit breaker has changed the balance of power. In some ways it has made it harder for the prime minister to order a temporary lockdown, because it would look as if he were caving in to pressure from the opposition. But that pressure could yet force a shift in policy. It might not be called a national lockdown, but if more of the country were moved to tier 3 and more restrictions were imposed on top of that, it would be a lockdown in all but name.

One of the important decisions is whether to add a week to the schools’ half-term holiday, which starts on 26 October in most of England. That is what Arlene Foster and Michelle O’Neill have done in Northern Ireland. Starmer insists that he does not want to “yank” children out of school, which Johnson accused him of advocating, but extending half-term by five days might be a way of fudging that.

My view is that Johnson is more aligned with Sunak than he appears to be, but that he has to manage a health secretary now seriously alarmed about NHS capacity, and a fearful public opinion – hence the significance of the Daily Mail’s front page on Friday: “An Epidemic of Madness.” Not to mention the complication of the war that has broken out with the northern barons of Labour cities.

This coming week could be a big test of the chancellor’s powers of argument.