In 1963, soon after becoming Labour leader, Harold Wilson told his left-wing supporters: “You must understand that I am running a Bolshevik revolution with a tsarist shadow cabinet.” The same was true of Jeremy Corbyn after his election last September. To the consternation of his ally Diane Abbott, his first shadow cabinet contained just three MPs who voted for him (Abbott, John McDonnell and Jon Trickett).

From the beginning, most of Corbyn’s supporters believed this team would not endure. In an interview shortly before he became the leader’s director of strategy and communications, Seumas Milne referred to it as “a stabilisation shadow cabinet”. The expectation was that an ideologically purer successor would follow. After Labour’s victory in the Oldham West by-election secured Corbyn’s leadership, his team seized the chance to act.

Despite its interminable length, the eventual reshuffle did not bring the transformation that some had anticipated. The shadow foreign secretary, Hilary Benn, remained even after his confrontation with Corbyn over Syria. Chief whip Rosie Winterton survived despite claims by the leader’s allies that she had exaggerated support for air strikes among MPs (one told me that the “whole project was fucked” unless she or her team were replaced). Not a single additional Corbynite was brought into the shadow cabinet.

Yet in other respects Corbyn significantly strengthened his position inside the party. Benn survived, following the threat of resignations in solidarity with him, but at the price of agreeing to abide by his leader on policy. There will be “no repetition”, sources emphasised, of the extraordinary moment when the shadow foreign secretary contradicted the leader of the opposition’s stance on Syria from the Commons despatch box. Rather than further free votes, the leadership’s intention is to enforce collective responsibility on future occasions. Corbyn’s allies point out that his 534 rebellions against the whip in parliament came from the back bench, not the front bench.

Maria Eagle, an unambiguous supporter of Trident, was replaced as shadow defence secretary by Emily Thornberry, an opponent of renewal. Corbyn will still struggle to avoid conceding a free vote when the Commons decides on the matter later this year. Deputy leader Tom Watson, who emphasises that he has his own mandate, is among the shadow cabinet members committed to renewal of Trident. But the unilateralists have advanced their position.

Corbyn sacked the shadow culture secretary Michael Dugher and the shadow Europe minister Pat McFadden, two of his savviest critics, for “disloyalty”. Labour sources maintain that “the new politics” allows “open debate” but not licence to “attack” the leader. Those who wish to push the limits of dissent have been served notice that their jobs are at risk.

The sacking of Dugher, whose recent New Statesman article opposing a “revenge reshuffle” Corbyn cited as justification for his removal, was privately opposed by Watson and the shadow home secretary, Andy Burnham. After their wishes were ignored, nine shadow cabinet members publicly lamented Dugher’s departure. But none resigned. Corbyn will feel liberated to sack others in future, now he has confirmed that an attack on one is not an attack on all.

On the morning of Dugher’s removal, several of the 12 former shadow cabinet ministers who refused to serve Corbyn told me they felt vindicated. Far better to force Corbyn to assemble a team of true believers and succeed or fail on his own terms.

As the reshuffle was covered in minute detail by reporters on the stairwell below the Labour leader’s office in the Norman Shaw South building, senior MPs melan­cholically reflected on what they regarded as its irrelevance. “The reshuffled post-holders almost certainly won’t get a taste of power,” a former shadow cabinet minister told me. “A fantasy government that will stay that way,” another said. Their des­pondency was increased by a YouGov poll, released mid-reshuffle, which showed Labour 10 points behind the Conservatives (23 points behind on the economy) and put Corbyn’s approval rating at -32. “You can rearrange the chairs around the table as much as we like. Until these numbers change we won’t win a general election,” the newly elected MP Wes Streeting said. Last month, for the first time since 1951, a Conservative government ended the year further ahead than at the time of the general election.

But in Labour’s internecine struggle such numbers are of little consequence. For Corbyn, who took office with unprecedentedly low support among MPs, the priority is to consolidate his control. Senior Labour figures express fury that the Tories have extended their advantage despite the floods debacle and the EU schism. But they realise that their rage is futile. Corbyn’s hegemony among members is undiminished after the exodus of tens of thousands of opponents. For both principled and political reasons, he is enacting the anti-war, anti-Trident mandate that his supporters gave him.

Even if the May election results are as uniformly dismal as some predict, few believe that Corbyn’s position will be endangered. Some of his opponents speak of the need to remove him before the 2016 conference, when they fear he will change policymaking and leadership rules to the left’s advantage. Yet there is little confidence that their self-imposed deadline will be met.

When Corbyn first became the front-runner it was often predicted that he would be unable to form a front bench at all. Just four months later, he has begun to remake his shadow cabinet in his image. In time, outriders such as Clive Lewis, Richard Burgon and Cat Smith, all first elected in 2015, will become candidates for promotion.

The original hope of Corbyn’s opponents in the shadow cabinet was that he would serve on their terms. The reshuffle has turned that calculation on its head. Corbyn has shown that he is determined to hold power, rather than merely office.