Root’s record-breaking feat has been lauded by a number of former England players, including the man whose record he has now surpassed.
“Root would have known [he had broken the record]. You just do, don’t you?” Cook told BBC Test Match Special. “And what a shot to do it.
“Probably for Joe Root now, he’s got bigger fish to fry.
“I don’t know what his exact aim is, but he’s not lost that hunger and desire to keep on scoring runs. Losing the captaincy and going back into the ranks wasn’t an easy thing. It’s as if it’s taken him to another level on consistency.
“That shot against Jasprit Bumrah in India, that infamous reverse sweep, he’s been averaging 75 or something since that moment.
“It’s extraordinary numbers for a player at that kind of level.
“It was kind of a reality check for him and I’ve never seen that hunger, determination or relentlessness in anyone’s batting really. He does that in an elegant way.”
BBC cricket correspondent Jonathan Agnew added: “It’s a tremendous achievement. He can tick that off, he’s done. I’m sure when he gets his phone out, one of the first people he will text will be Alastair Cook.
“It’s highly likely that whatever Root’s final [Test run] tally will be, it will never be beaten.”
Among the England greats Root has passed in recent years are David Gower and Michael Atherton, both of whom were in Multan to witness him reach the top of England Test run-scoring list.
“It’s a remarkable achievement, he’s been a remarkable player,” Atherton said on Sky Sports.
“He’s been so consistent over the years and he’s done it in a way which is so pleasing on the eye. Nasser Hussain so often references Root’s character.
“He’s a very nice lad, which adds another element to it. Sportsmen should be judged on sport but if you’re a good lad with it, that’s an extra notch too.”
Gower added: “It’s an extraordinary feat. Both Alastair and Joe mastered the art of scoring runs in big quantities and mastered the art of staying at the crease long enough to make big runs.
“They have slightly different styles. I think even Alastair will admit Joe Root has an easier-on-the-eye style than he did but both had supreme qualities and determination.
“In Joe’s case, he seems to enjoy it so much that the thought of getting out is so painful.”