Jamie Porter adopted the mantle of supersub when he came off the proverbial substitutes’ bench to rip through the Sussex batting at Chelmsford.

Porter, rested by Essex for this Rothesay County Championship match, was called into post-lunch action after the pacey Charlie Bennett limped off – and out of the game – with a leg injury sustained during the morning session. The limb was later described as ‘sore’ and was being assessed.

Porter struck in his fifth over on the way to taking his season’s tally to 28 wickets. His 3 for 32 from a dozen overs blasted a large hole in a plodding Sussex performance. Their batsmen invariably hung around for a while, but without accumulating runs at a rate higher than 2.3 an over, and then got out.

Dan Hughes underlined that with his 45 embracing 107 balls, as Essex’s seam attack of Sam Cook, Shane Snater and Zaman Akhter maintained tight lines mixed with deliveries that either took the edges of bats or just missed them. When bad light cut 10 overs off the day’s allocation, Sussex had reached 213 for 7 with Jack Leaning unbeaten one short of a half-century

Tom Haines’s decision to bat first on a wicket with plenty of grass left on it had looked debatable at best. The Sussex captain must have rued calling correctly when he was the first of two wickets in three balls for Cook with only seven runs on the board. Both Haines and Tom Clark were caught behind to similar inswinging deliveries, the first representing the 500th dismissal of Cook’s professional career, the second Pepper’s 200th victim.

Under heavy skies, and with the floodlights on within the first hour, play became attritional. The ball barely left the square as the Sussex third-wicket pair of Hughes and Charlie Tear took 19 overs to piece together the first fifty of their partnership.

The stand was worth 72 when Hughes drove loosely at Snater and the ball flew sharply into the slips where Simon Harmer parried it into the air for Paul Walter to complete the catch. Enter Porter, who had his first wicket when Tear dangled his bat and nicked to first slip.

James Coles’s unhappy time at the crease since his double century against Glamorgan in mid-June continued when he hung his bat out to the first ball of Akhter’s latest spell and gave Pepper his 201st scalp.

Porter was back among the wickets soon after tea when he got one to swing late and trap John Simpson lbw. Ten balls later he had Jack Carson edging to first slip.

Dom Goodman showed some attacking intent by twice lofting Matt Critchley to long-on for a six and a four in an over. Yet even with that outburst his eighth-wicket partnership with Leaning took 17 overs to post fifty for their unbroken eighth-wicket stand.