Rishi Sunak claimed to be the candidate of change at the Conservative Party¡¯s annual conference a few weeks ago.

But the man who aspired to tear up 30 years of ¡°failed consensus¡± politics lacked conviction. A former school head prefect was always going to be an unlikely rebel.

Now Sunak has dropped the pretense by picking David Cameron, his Conservative predecessor who called and lost the U.K.¡¯s referendum on Europe, to be foreign secretary. After the sound and fury of the Tory Party¡¯s eruptions last week, a new vision emerges: Everything must change at the top so that everything can remain the same.

Allies of Sunak ¡ª and Cameron ¡ª compare the latter¡¯s comeback to Edward Heath¡¯s choice of his predecessor, Alec Douglas Home as foreign secretary in 1970. They might also point out that Neville Chamberlain loyally served in World War II under Winston Churchill, his long-time party rival. But the ferocious Heath was never in awe of his mild-mannered colleague and Chamberlain died six months into serving his new boss.

Cameron was prime minister from 2010 to 2016, leader of his party from 2005 and fought and won two elections. Sunak has scarcely been in the job for 12 months. There is no precedent in modern times for such an imbalance in seniority at the summit of power.

Desperate times, however, call for desperate measures. The next general election is only a year away and Sunak has chosen to go down fighting with a team he can at least trust to not to undermine him. Cameron brings experience and unflappability. Too many of his colleagues lack that quintessential Westminster quality called ¡°bottom¡± ¡ª in the sense of heft and hinterland rather than expansive behinds. In a similar fix, the Labour Prime Minister Gordon Brown recalled his ¡°frenemy¡± Peter Mandelson to office 15 years ago, stabilizing his shaky administration.

When he first won the keys to No. 10, Sunak tried balancing the warring factions within the Tory tribe around his Cabinet table. The party¡¯s right wing was given leave to wage wars on wokeness and transgender rights, while he reassured the markets by returning to Cameron-era fiscal austerity and mending relations with the European Union. Experience was thin on the ground after Brexit and four divisive leadership contests had taken their toll. Critics mocked that his inexperienced government was a ministry without all the talents.

The voters quickly sensed it, too: the Tories trail by a consistent 20-point margin in the opinion polls. That deficit emboldened Sunak¡¯s home secretary, Suella Braverman, to flout collective Cabinet responsibility last week and has incited other potential leadership candidates to audition for his job. Put bluntly, Cameron has returned from...