The conundrum that is the No 3 slot is heading towards a resolution. Something very odd would have to happen for Jonny Bairstow not to continue there when England next embark upon a Test match, in Bridgetown, Barbados, on 23 January.

Here in sapping heat, Bairstow hit his sixth Test century and one of his most cherished on his return to the team. And he was batting at No 3. This must have been a relief to the management as well as Bairstow himself. England are adopting the policy of selecting their best available batsmen regardless of where they usually bat, and in these conditions, where pace bowlers are little more evident than a lesser-spotted woodpecker, that seems an eminently sensible idea. In fact this theory may well work better for them than any other whatever the conditions.

Bairstow strode on to the ground purposefully after Rory Burns’ dismissal, stretching every sinew, playing shadow strokes and occasionally breaking into a trot. He looked like a man who meant business. To his first delivery he produced a measured drive, which sent the ball trickling over the boundary at extra cover, and there were remarkably few alarms thereafter. When Bairstow was on 10 Sri Lanka persuaded themselves that he had edged against Malinda Pushpakumara and reviewed without success, one of two mistakes in this department which would prove costly since the home side were unable to review when the umpire Chris Gaffaney somehow decided to give Ben Stokes not out before he had scored.

Bairstow has always been a forthright player of spinners and before long he was playing the increasingly trendy sweep shot as well as plonking a blameless delivery from Pushpakumara way over the midwicket boundary. He reached his half-century in 76 balls and became slightly more circumspect as he realised that there was a century for the taking. His second 50 occupied 89 balls.

There were times when he appeared to be suffering from cramp as a consequence of such unaccustomed prolonged activity, but Bairstow knows that centuries are not forgotten. So he gritted his teeth. They can deprive him of the gloves but now they cannot leave him out of the team.

Upon reaching his 100 his reaction was unusual: there were no smiles, but a stony-faced roar of relief which seemed a potent mix of concealed elation and anger; his helmet was removed, he tossed his bat to the ground and received a little hug from Stokes. Still no smile was evident. Clearly – and unsurprisingly – this meant a lot to Bairstow. Leaving aside the emotion, this was an innings of the highest quality, and the first hundred from an England No 3 in 52 attempts.

There was always some help for the spinners from this pale-brown surface but it was not so pronounced as in Kandy. The ground was well-populated but the vast majority of the spectators were England supporters, who would be bizarrely entertained by snippets from Culture Club, Neil Diamond and John Denver in between overs. There can barely be a Test arena left – outside of Australia – where the England players feel as if they are playing away from home.

For the eighth time in a row Joe Root won the toss, which put him alongside Ray Illingworth and Wally Hammond in that facet of the game. It was another good one to win. Burns started busily and, perhaps, too ambitiously. He gave himself a lot of room to cut against Dilruwan Perera and the ball hit his off-stump while he was stationed some distance outside leg. Soon after Keaton Jennings tickled the ball straight into the hands of Roshen Silva at leg slip off Pushpakumara.

Root began impishly and was soon into his sweeping routine. On 18, Sri Lanka wasted their second review when England’s captain was facing Lakshan Sandakan, the intriguing left-arm wrist spinner, after which the two Yorkshiremen raced along. They had added 104 when Root top-edged a slog-sweep against Sandakan and was caught at midwicket.

Stokes should have been out lbw to his 14th delivery from Perera when he had yet to score; he might have been given when sweeping against Dhananjaya de Silva on 26. In the end he was caught at slip off Sandakan for 57, which included two mighty slog-swept sixes. How Sri Lanka suffered from those ill-judged reviews. On 102 Bairstow was another beneficiary when missing a sweep against Sandakan. He missed again when sweeping on 110 and was bowled.

Now England lost some momentum. Moeen Ali was dropped on two behind the stumps and on 17 at slip but a sharp return catch by Sandakan accounted for Jos Buttler and gave the wrist spinner his fourth wicket of the innings. Then Ben Foakes was caught behind for 13 on a day when fresh legs and minds prevailed, those of Sandakan and – most emphatically – Bairstow.