Kent were made to toil in the field and trail Essex by 247 runs with nine wickets left after day two of the sides’ County Championship Division 1 clash at Chelmsford.

Declaring on 458-8 after ending day one 106 without loss, the hosts had the added bonus of a Kent wicket with the last ball of the evening, Tawanda Muyeye lbw to Sam Cook for a duck.

Matt Critchley’s second century of the season had put Essex in the driving seat on a strange day of substitutes and concussion repercussions.

The 26-year-old faced just 168 balls in rattling up 117 runs as Essex put Kent to the sword while building a first-innings lead of 251. Critchley entered at 158-3 and departed 64 overs later on 408-7 when he picked out long-leg to give part-time spinner Jack Leaning a rare wicket.

In between he shared a century stand with Simon Harmer - who hit a swashbuckling season’s-best 83 not out from 92 balls - and other partnerships worth 71 and 49 with Paul Walter and Adam Rossington respectively. In the process the former Derbyshire all-rounder took his season’s tally in the Championship past 700 runs.

“It’s probably not been our best day when you look at the scoreboard,” said Kent bowling coach Simon Cook, “but having said that the first two sessions we held them really, really well.

“We had plenty of opportunities, we had three or four clear chances which unfortunately we couldn’t take. We actually bowled two really good sessions up to tea.

“We knew they were going to start to come hard and unfortunately we couldn't really hold on to those chances and they came to bite us in that last session when they put us under a bit of pressure. As a result we end up batting this evening rather than batting an hour into tomorrow.

“It’s one of those pitches that once you get in you can start to score. It’s a tough pitch to start with. Spin is obviously going to play a big part tomorrow, but once you get in it does allow you to free your arms. It’s a fast-scoring ground as we’ve seen in the T20s.

“It’s a frustrating day having controlled two sessions really well, created plenty of opportunities and we didn’t capitalise on that in the last session.

“Tomorrow is going to be trying to take as much time out of the game as possible by batting sensibly. I still think we’ve got to put pressure on, certainly the likes of Simon Harmer, who I think Grant Stewart showed in the first innings didn’t let him settle. It’s a different proposition when we’re putting pressure back on.”

Sir Alastair Cook had laid the foundations with a 176-ball 87, but some late six-hitting by Critchley, Harmer and Doug Bracewell gilded the lily. Hamid Qadri bore the brunt with figures of 3-120, while Arshdeep Singh returned best Championship analysis of 3-58.

But the real drama of the day came before play with the news that Essex’s Nick Browne had retired hurt after feeling groggy overnight and failing an off-field concussion test. The left-handed opener was hit on the head by a short ball from Singh in Wednesday’s evening session but batted on for a further two-and-a-half overs before being visibly ill after the penultimate delivery of the day. He then passed an on-field check and saw out the over.

Robin Das, who had originally stood in as the nominated substitute while Dan Lawrence made his way back from Old Trafford where he was stood down by England, then became Browne’s replacement.

Das lasted five balls before he became another entry in the scorebook that needed an asterisk: the concussion substitute was caught by Kent substitute wicketkeeper Harry Finch, standing in for Jordan Cox who further depleted the visitors’ resources with a thigh injury.

Having put on 117 for the first wicket, thanks to the efforts of three men - but mainly Cook - Essex lost another almost immediately when Tom Westley was trapped lbw to give Arshdeep a second wicket.

Cook had looked in sparkling form the night before, stroking a dozen boundaries in his 64. But he batted for a further hour-and-a-half in the morning session, adding just 23 runs from 70 balls before looking a little disconsolate at being judged lbw to former Essex seamer Matt Quinn.

Lawrence, having made the journey down from Manchester, played an entertaining cameo of 25 that included an effortless six over midwicket before he attempted to sweep Qadri in a similar direction - only to become a third lbw victim.

Critchley hammered Qadri over long-leg for the six that took Essex beyond Kent’s first-innings 207 with only four wickets down, though it had taken them 17 overs longer. However, Walter’s 90-ball 45 was ended by the third delivery with the new ball as he played down the wrong line to Arshdeep.

Rossington twice straight-drove Joey Evison for fours in a bright partnership with Critchley before he was deceived by Qadri’s flight and turned to see his stumps disturbed.

Once Harmer had got off the mark to his 28th ball, he cut loose and needed just another 51 balls for his half-century, reached with a huge six off Qadri. But it was Critchley who caught the eye with some breathtaking, but orthodox, hitting and he reached three figures from 161 balls by pulling Quinn through midwicket for his 14th boundary that included two maximums.

Harmer, with five maximums, traded maximums with Bracewell off the beleaguered Kent spinners before the New Zealander was stumped to prompt the declaration.