As English conservatives, and soon all of England, turn the page on the Boris Johnson premiership, his brief if eventful tenure is already generating both praise and scorn. Supporters point to Brexit, the 2019 electoral triumph, and his leading support for Ukraine. Detractors highlight Brexit, partygate, and pricey renovations at 10 Downing Street.  

While Brexit will garner the most inches of print in the history textbooks of the future, another achievement of Mr. Johnson bears noticing: his refashioning of the Conservative Party from a smoke-filled back room populated with aristocrats into a big tent, its dimensions capacious along the lines of both race and class.

One of the most remarkable signatures of this transformation is the slate of candidates to replace Mr. Johnson. Of the 11 persons vying for 10 Downing Street, six are racial minorities. In contrast, the contest to lead the Labor Party, which bills itself as the van of progressivism, last featured an all-white slate. The Tories have had two female premiers; Labor has had none.    

The Cabinet Mr. Johnson appointed after his smashing electoral win in the 2019 elections was the most diverse in British history, with six ministers, or 18 percent of the total, hailing from minority backgrounds. In this respect Mr. Johnson built on initiatives undertaken by a Conservative predecessor, David Cameron.  

That investment could now pay off in the form of a remarkable sight: a prime minister of Her Majesty’s Government whose family hails from land the Crown once ruled.      

This transformation is evident at the party’s summit, in two of the leading candidates to replace Mr. Johnson. Nadhim Zahawi was born in Baghdad, once the seat of a British Mandate, to a Kurdish family; he moved to England during the early years of Saddam Hussein’s reign. Mr. Zahawi headed the U.K.’s vaccine distribution and then served as secretary for education before landing as chancellor of the exchequer.

“I am the British dream,” Mr. Zahawi has said of himself. 

The man Mr. Zahawi briefly replaced and another frontrunner for 10 Downing Street, Rishi Sunak, is also an immigrant, the son of parents born in East Africa and the grandson of Indians from Punjab province, the jewel in Queen Victoria’s English crown.  

While Mr. Sunak’s background might suggest an underdog, his career has been a gilded one, augmented by his time in finance and his father-in-law’s status as the founder of Infosys. His family wealth has emerged as an electoral liability, but Mr. Sunak’s announcement of his candidacy focused on his immigrant background.

Yet another top-tier candidate who hails from the provinces of the empire is a one-time health secretary, Sajid Javid, the son of Punjabi Pakistani farmers. Mr. Javid, who went on to serve as an aide to Rudy Giuliani during the latter’s successful 1993 mayoral campaign and a starry career in finance, has now thrown his hat in the ring to replace the man he served for years. 

It was the twin resignations of Messrs. Sunak and Javid that signaled the end of Mr. Johnson’s time as prime minister, and the opening bell for their competing efforts to replace him. They will be joined in the jockeying by MP Kemi Badenoch, who resigned last week as minister of state for equalities. Her family has roots in Nigeria, which was a British protectorate between 1901 and 1960. 

While there is no clean precedent for the trajectories of these aspirants for the prime minister, there are rough analogues. In recent years, both Gordon Brown and Tony Blair served in the top post while hailing from Scotland, which was invaded by England in 1296 and still chafes under even devolved English rule, angling for a referendum on independence next year. 

A more apt template might just be arguably the greatest Tory of them all, born not in Bombay but Bloomsbury but in his own way unlikely to be surpassed as the most improbable prime minister of them all. The First Earl of Beaconsfield, Benjamin Disraeli, was baptized as a child but was considered Jewish by everyone, most of all himself. He was Queen Victoria’s favorite PM. 

Disraeli’s path to power was more arduous than any of the current crop of Conservatives will traverse. He served in Parliament for three decades before landing the top job, then lost it again, only to gain a second tenure six years later. 

Today’s Conservatives — and, for that matter, Mr. Johnson himself — would do well to remember the remarkable Disraeli, who, because he himself was more the heir of shtetls than Sussex, crafted a party of the future rather than the past. Or they might just swipe one of his most famous bon mots: “never apologize, and never explain.”