The highest Test score ever lodged by an England wicketkeeper in a home Test followed by a perplexing dropped catch. For Jonny Bairstow, even on the most exultant of days the debate about whether England should utilise him as a wicketkeeper or specialist batsmen is destined to ring loudly.

Bairstow was left unbeaten on 167 as England were dismissed for 416, 45 minutes into the afternoon session on the second day at Lord's, but Sri Lanka ended the day strongly by reaching 162 for 1 with Kaushal Silva becoming just the second player to score half-centuries in his first three Test innings at Lord's.

Spritely of mind and stroke, Silva delighted in every opportunity to dart his runs between cover and third man. All three England pace bowlers - James Anderson twice at Headingley, Stuart Broad and Steven Finn at Chester-le-Street - had shared in four successive catches from Silva for Bairstow in this series, but on a surface with few devils his outside edge this time looked less compromised. He played with positive intent from the outset to spearhead Sri Lanka's most productive batting display since they arrived on these shores.

Bairstow's innings was the highest by an England wicketkeeper on home shores and only six runs short of Alec Stewart's all-time record. His authority as a batsman is growing apace. With three Test hundreds in eight knocks, it was a time for celebration. Here, said some, was England's Adam Gilchrist.

Then came the wobble. Whether it was the Lord's wobble - the ground is notorious for the ball swinging late after passing the batsman - or the Bairstow wobble - equally notorious - will be debated long into the night. Bairstow did have to contend with some late dip after the ball shaved Dimuth Karunaratne's edge, but he missed the ball by a considerable distance as it hit him on the thigh.

Chris Woakes, an undemonstrative sort, cast his hands apart in disbelief as he was denied a wicket with his first ball; Bairstow widened his eyes as if the ball had turned into a Christmas pudding upon its final approach. Karunaratne was reprieved and Sri Lanka, scooting ahead on another placid Lord's Test pitch, closed with deserved satisfaction. After two heavy defeats in the frozen north they have thawed out impressively. Sri Lanka love Lord's.

Bairstow is not the first wicketkeeper to be embarrassed by Lord's capricious ways. Mention of Stewart invites discussion of another England player whose career constantly shifted between a role as batsman or batsman-keeper. Bairstow openly resents the debate surrounding his role far more than Stewart ever did - Stewart preferred a straight-backed Do My Best For England barked response, but it will be discussed all the same.

Long before the close of the second day, he looked exhausted. His body ached after 408 minutes at the crease, a bruised finger was on his mind no matter how much he tried to block it out and, considering that his valiant efforts had provided a get-out clause for poor England batting, some of the throws he received from England teammates were lazy enough to have deserved a bawl-out. He was a man in need of an early night.

Karanaratne, 28 when he was reprieved, is not the type to punish such an error: his Test career is awash with 20s and 30s. Spared an lbw verdict three runs later when England unsuccessfully reviewed Woakes' inducker he then became becalmed, as if aware of his reputation, then suddenly spurted like a tap with a faulty washer with three successive boundaries off James Anderson.

"Keep going," tweeted Sri Lanka's chairman of selectors, Sanath Jayasuriya, as both batsmen reached half-centuries in the same over, Sri Lanka's first century opening stand raised for two-and-a-half years Instead, Karunaratne nudged Steven Finn off his hip to Bairstow. Tweets are yet to be read between balls by batsmen at the crease, although one suspects it is only a matter of time.

Silva did graze contentedly to the end against an England attack where only Woakes, the fastest England bowler in terms of a single ball and average, possessed much exuberance.

Tranquillity washed over the day from the outset. Matt Prior, after ringing the bell at start of play, was invited on to the England balcony to catch up with old mates and down below Bairstow and Woakes made serene progress to their highest Test scores against a Sri Lanka attack that was as unthreatening as England's was to prove later.

England's slightly dicey overnight position of 279 for 6 was suitably refined to 384 for 7 by the time the clock reached 1pm. Woakes was the only wicket to fall before lunch, frustrated by Herath's over-the-wicket approach into the footholes outside his leg stump and advancing to chip a return catch. But he did have his first Test half-century, 66 from 142 balls, an innings characterised by genial off-side drives.

England have got 400 in the first innings in a home Test and lost before, but not since 1998 when Muttiah Muralitharan was rampant at The Oval and his 16 wickets in the match enabled Sri Lanka to pull off an unlikely heist. A dominant Sri Lankan Saturday, with few wickets lost, would cause a quiver or two.

But these days Sri Lanka have no Murali and, indeed, one wonders how long they will have the benefit of the excellent Herath. He is 38 now, and remains a master of little subtleties, drawing one or two nods of appreciation from Bairstow as he coaxed him into minor errors of judgment.

Serenity is hardly Bairstow's calling card. Watch him bat at his most combative and one imagines he could fight his own shadow. But with a century gathered in 11 balls before stumps on the first day, his appetite to take advantage of placid batting conditions was evident from the outset and the moments of fortune that had helped him through the opening day were absent.

Woakes shared in a sixth-wicket stand of 144 in 40 overs as Sri Lanka's seamers made no impression. He is very much the anti-Stokes, as peaceful as Stokes is belligerent; as unobtrusive as Stokes is the centre of attention. If he saw a locker door upon dismissal, he would check it was safely closed not punch it in anger. In such, he does not fit modern fashions, but his first fifty - at the 11th attempt - will have won him respect, if not celebrity status.

England's innings subsided quickly after lunch with the last three wickets falling in the space of six overs. Stuart Broad made a typically insecure appearance before slashing Suranga Lakmal to gully, Finn - after surviving an lbw decision for Herath on review - top-edged the same bowler to deep backward square and Anderson was caught at the wicket, defending a short ball from Shaminda Eranga.