Prior to Saturday, Root’s highest score in all cricket against the old enemy was 92 not out, made in a T20 Blast match at Old Trafford in 2016.
His highest score in six County Championship Roses innings was 22.
It would have been something of an anomaly had the greatest English batsman of his generation, let alone the greatest Yorkshire batsman, gone through his entire career without a three-figure score against the Red Rose, so Root put that right in the Headingley sunshine, making 147 to the delight of most in a crowd of 1,645 on the warmest day of the year so far.
Root’s 37th first-class century – and his highest score for Yorkshire for six years – underpinned a third day total of 356-8 as the hosts replied to Lancashire’s first innings 566-9 declared.
He arrived at the crease after Tom Loten, the nightwatchman, fell to the final ball of the day’s fifth over, trapped leg-before by a slow full toss from Tom Bailey, which left the hosts 62-3 and left the bowler prone on the ground after he slipped in the act of delivering the ball.
Root got off the mark by glancing James Anderson to fine-leg for a single, the battle between them always compelling, but the fourth wicket fell to the next delivery, George Hill miscuing a short ball to mid-wicket. At 68-4, still 498 adrift, Yorkshire were in transparent trouble, but Root and Harry Brook combined in a run-a-ball partnership of 66 to emphasise the placid nature of the pitch, the pair totally dominating the Lancashire attack.
Brook made 41 of the runs, from 33 balls with nine boundaries, and produced some of the best shots of the match in the process only to then perish out of the blue and miss out on his quest to become only the fourth Yorkshire player to achieve seven successive scores of 50 or more in first-class cricket, after Geoffrey Boycott, Darren Lehmann and Anthony McGrath.
He was bowled by leg-spinner Matt Parkinson as he tried to work a leg-break through the on-side, the ball spinning past the outside edge and knocking down the middle stump.
Yorkshire remained in peril at 134-5 with Brook’s dismissal, but Root found an ally in young Harry Duke, who put behind him some difficult times with the gloves to provide mature and stubborn support.
They batted throughout the balmy afternoon, Root going to his century shortly before tea following a masterclass of confident drives, clinical sweeps and careful defence, the innings constructed with something of an inevitable air.
Duke fell for 40 in the evening exchanges and in incongruous manner, bowled trying to ramp Parkinson having otherwise shown tremendous patience and discipline during a 201-ball stay at the crease.
His departure left the door ajar at 288-6 and it opened further when Yorkshire lost two wickets with the total on 331, Dom Bess plumb leg-before to Bailey and Root caught at slip off Parkinson as he tried to work the wrist-spinner, operating from around the wicket at The Howard Stand end, through the leg-side.
The disappointment ethced on Root’s face as he left the field betrayed the fact that the job was not finished. In total, he faced 218 balls and hit 13 fours.
Jordan Thompson and Steve Patterson survived until stumps, the former’s position at No 9 emphasising Yorkshire’s strength in depth, with 61 more required to avoid the follow-on.