It was like watching Eliud Kipchoge run: the pace was remarkable enough in itself, but the ability to sustain it across such a long period of time defied logic. Harry Brook batted for seven hours, spending 97.4 overs in the stifling heat and facing 322 balls - all while scoring at a run a ball. This was Brook’s Multan marathon, an epic feat of endurance and stamina.

Brook is 25 years old, and this was the first time in his lifetime that an England batter had scored a triple-century; his 317 was the fifth-highest score in England’s Test history. This pitch was desperately flat, offering nothing to Pakistan’s weary bowlers, but Brook put on a batting clinic which laid bare both his singular focus and his hunger for runs.

This was not an innings that Brook could have played 12 months ago. He missed England’s tour to India at the start of the year to be with his grandmother, who was on her deathbed, and spent the time away from cricket “trying to lose a bit of weight and trying to get leaner”. It has reaped rewards, allowing him to withstand the physical challenge of batting in these conditions.

“That three-month period I had at the start of the year was massive for me,” Brook said. “I obviously lost a bit of weight, and tried to get as fit as possible by eating well, running and gymming. If I hadn’t done that, I’d have probably got to 150 and just slogged one up in the air. It’s made a difference, for sure.”

Brook ran and ran and ran. During Brook’s time in the middle, the vast majority spent alongside Joe Root in a mammoth 454-run partnership, England scored 199 singles, 55 twos and 11 threes: he covered more than four miles running between the wickets alone. He looked utterly exhausted when celebrating his double-hundred, after batting through the first session.

Yet after a nutrition shake, some food and plenty of fluids at the interval, Brook found another gear after lunch. He scored 99 runs off 65 balls in the afternoon session as he laid into the occasional spin of Salman Agha and Saim Ayub, whom he swatted disdainfully down the ground to reach 300. It was outrageous batting, and his scoring rate enabled a declaration before tea.

Until he miscued a sweep to backward square leg on 317, Brook looked as though he had a realistic opportunity not only to break England’s record score, Len Hutton’s 364, but to overtake Brian Lara’s world-record 401 not out too. He did not offer a genuine chance at any stage in his innings, or even have a review to worry about.

His one scare came on the third evening. On 75, Brook defended a ball from Aamer Jamal into the crease, only for it to bounce up and hit him on the chin. It dribbled past his attempt to kick it away and into the stumps, but was moving so slowly that it did not dislodge the bails. Having seen both Zak Crawley and Ben Duckett give hundreds away, Brook resolved not to.

It was only a month ago that Brook was bored out by Sri Lanka’s seamers at The Oval, letting his frustrations get the better of him as they hung the ball wide outside his off stump. His character and mentality were called into question: this innings was an unequivocal response to that criticism.

Perhaps Pakistan should have borrowed the same template. “Our plan was to bowl pretty straight - and when we did that, we did quite well,” Jason Gillespie, their coach, said on the third evening. “But on reflection I would’ve just liked us to just sit in a bit longer, be a little bit more patient and just a little bit more disciplined.”

They occasionally tested out the perception that Brook has a weakness against the short ball, and proved that the theory is not watertight. When Shaheen Shah Afridi slammed the ball in halfway down, Brook simply ran down the pitch, gave himself room and flat-batted him away for four.

Brook at his best reduces batting to its first principles, hitting the ball where the fielders aren’t. It was the theme of how he played on the fourth day: charging down to launch Jamal over cover; standing dead-still to uppercut Naseem Shah’s short ball over third man, and falling over to the off side to scoop over his left shoulder.

This innings also extended Brook’s scarcely believable record in Pakistan, the country where he has felt “at home” since playing for Lahore Qalandars in the PSL two-and-a-half years ago. In fact, he has been significantly better there than when actually playing at home: Brook has now scored more Test runs in Pakistan (785 in six innings) than in England (761 in 21).

Root was on 82 when Brook came in at No. 5 on the third afternoon; by the time he was dismissed for 262 on the fourth, Brook had 260. Their partnership was the biggest in England’s history and a combination between the two Yorkshiremen who fuse the past and the future of their Test team with the present.

After overtaking Alastair Cook on Wednesday, Root will likely put the England record for Test runs out of reach in the next few years. If there is anyone who can catch him from their current batch of young batters, it is surely Brook: this was his first double-hundred in first-class cricket, let alone triple, but he has a rare blend of talent and temperament.

Brook will face new challenges next year: his first full series against India, whom he has only played once, and his first tour to Australia. It remains to be seen how he will fare against two of the world’s best attacks on pitches that will pose more issues than this one, but the evidence of his career so far suggests that he should be up to the task. –Cricinfo