LONDON — When Prime Minister Boris Johnson of Britain convened his new cabinet on Friday, it looked less like a conclave of powerful government officials than a well-mannered classroom on the day the headmaster came to visit.

“How many hospitals are we going to build?” Mr. Johnson asked.

“Forty,” they replied in unison.

“How many more police officers are we recruiting?” he demanded.

“Twenty-thousand,” they chanted.

Such a display of lock step discipline is a striking change in a country that became used to clamorous politics under Mr. Johnson’s predecessors, David Cameron and Theresa May, who struggled to hold together balky coalitions and govern without a Parliamentary majority.

In the two months since Mr. Johnson won a landslide election victory and rolled up an 80-seat majority, he has moved rapidly to take control of the levers of power. And to a degree unmatched by any British leader since Tony Blair, the government is now almost entirely subordinate to him.