Brook's captaincy of the white-ball team was in jeopardy prior to the World Cup as it emerged that not only had he gone drinking the night before an international match during the pre-Ashes tour of New Zealand, he'd also provided a misleading account of a night that ended with his being hit by a bouncer.
Combined with some dumb dismissals in the Ashes questions were asked about his maturity on and off the pitch.
England took the view that he was a young man still learning about his responsibilities, and backed him to absorb the lesson.
In Pallekele on Tuesday Brook took on the responsibility of moving up to No.3 in the order, then batted beautifully and sensibly as England chased down Pakistan's 9-164 with five balls to spare.
England were struggling at 3-35 after the recalled Shaheen Shah Afridi (4-30) ripped through the top order, and again at 4-58 but partnerships of 45 and 52 with Sam Curran (16) and Will Jacks (28) took England to the brink of victory.
A late wobble in which Brook, Jacks and Jamie Overton perished for six runs in 12 balls gave Pakistan hope, but Jofra Archer hit the first ball of the last over for four to seal the win.
"Very happy with the way we played, nice to get through to the semis," said Brook. "There's areas we want to improve on, you can never get perfection but we are always striving for it."
Of his promotion he added: "Baz (coach Brendon McCullum) came to me this morning and said we might put you No.3 today. I haven't done it much but nice to get to face as many balls as possible."
Pakistan, whose first match against New Zealand was washed out, had opted to bat first. "It looks like a good pitch. We want to put up an above-par score and defend that," Pakistan captain Salman Ali Agha said.
However, Salman found himself at the crease in the third over, and back in the hutch in the fourth after smearing Liam Dawson to Overton at long-off.
As Archer had already done Saim Ayub for pace Pakistan were 2-27 but the in-form Sahibzada Farhan and out-of-form Babar Azam steadied the innings.
The scoring rate, however, struggled to get above seven-an-over and in the 11th over Babar was bowled swishing wildly at Overton for a 24-ball 25.
Fakhar Zaman joined Farhan and they both launched Jacks into the crowd in the 14th over as Pakistan sought to accelerate.
But Farhan, after striking Overton for 4,6 was leg before next ball for 63 off 45. Then Zaman also went straight after hitting a six, well held by Dawson off Rashid for a 16-ball 25 and it needed Shadab Khan, run out off the last ball for an 11-ball 23, to lift Pakistan to a competitive score, if not the "above-par" one Salman wanted.
Shah Afridi's pace and the wiles of Usman Tariq (2-31) kept Pakistan in the game but Brook's 50-ball century, with four sixes and 10 fours, carried England into their fifth successive T20 World Cup semi.
16°C