Essex 315 for 8 (Cook 127, Liddle 4-54) beat Gloucestershire 286 for 8 (Mustard 90, Cockbain 79, Bopara 3-34) by 29 runs
Alastair Cook served up his tenth career List A century to guide Essex to their third win in three Royal London Cup matches this season.
Cook paced his innings with some devastating hooks and pulls, to go with well-judged nudges, accelerating from the halfway point to reach 127 as Essex posted a formidable 315 for 8 from their 50 overs. Although Phil Mustard and Ian Cockbain laid the platform for Gloucestershire's reply with a third-wicket stand of 95 in 15 overs, they eventually fell 29 runs short after a late clatter of wickets.
Cook's first fifty took 65 balls, his second 20 balls less, while at the same time his boundary tally went up from three for the first to six for the second. When he was finally out, he had faced 134 balls and hit 12 fours.
Cook shared partnerships of 82 with Nick Browne for the first wicket, 99 with Varun Chopra for the third and 57 in six overs with Ravi Bopara for the fourth. Bopara marked his 32nd birthday with a 23-ball 37 during which he passed 9000 career List A runs, before taking three wickets to help finish Gloucestershire off.
As Essex chased late runs to pass 300, left-arm seamer Chris Liddle came back to claim three wickets in his last 20 deliveries to finish with 4 for 54.
Gloucestershire's requirement started at nearly six-and-a-half an over and had hit 10 with 10 overs to go, but Mustard (90) and Cockbain (79) traded big hits before the wicketkeeper departed after slamming seven fours and two sixes. Jack Taylor also joined the party with a six in his 25-ball 34, but it was not enough as Gloucestershire lost 4 for 29 in 5.3 overs at the death.
Essex were put in and Browne took the opportunity to bat himself back into form in his 40-ball 42. The left-hander survived a sharp caught-and-bowled chance to Liam Norwell before he was the first to go as he clipped Benny Howell off his legs to Michael Klinger at midwicket.
Cook settled and accumulated steadily but, the ball after he reached his half-century with another single into the covers, he lost his second partner when Tom Westley chased one outside off stump from Liddle and was caught behind for 5. Cook was dropped on 67 when he pulled Norwell to the midwicket boundary where Jack Taylor not only floored the catch but helped it over the ropes.
Having moved Essex from 101 for 2 to bring up 200 with Cook, Chopra took an ill-advised run to Chris Dent at mid-on on 41 and was three yards from home when the direct throw broke the wicket. Cook and Bopara then kicked on before the younger Taylor, Matt, claimed a catch low down at deep midwicket off Tom Smith to send back the allrounder.
Cook followed three runs and five balls later when he drove Liddle uppishly to Kieran Noema-Barnett at extra cover. The same Gloucestershire partnership accounted for Ashar Zaidi before Ryan ten Doeschate went lbw to Howell. Simon Harmer brought up the 300 with an extravagant reverse-sweep for four before Adam Wheater was caught behind from the final ball of the innings.
The Gloucestershire openers had put on 74 in 17 overs when Harmer turned one away from Klinger and Zaidi tumbled backwards in taking the catch at short third man. The batsmen had become bogged down and Dent underlined the frustration when he tried to hit Harmer over the top and found sub fielder Callum Taylor at long-off.
With the required rate rising, Mustard decided to chivvy things along and pulled Harmer for six to bring up his fifty from 63 balls. Cockbain then deposited ten Doeschate for a huge six over cow corner and Mustard hit another out of the ground at midwicket to ruin Harmer's figures, the offspinner ending with 2 for 69.
The return of Matt Quinn broke the third-wicket stand when Mustard sent a leading edge high to deep extra cover, where Cook claimed it at the second attempt. Noema-Barnett didn't last long before holing out to Taylor on the midwicket boundary, but Cockbain kept up the tempo and reached his fifty from 51 balls.
Jack Taylor and Cockbain slammed straight sixes in the 42nd over, as Wagner made a costly return that leaked 21 runs and ended with Cockbain being caught off a free hit. But after helping put on 70 in nine overs, Taylor tried to hit Quinn over wide mid-off and was pouched by Harmer.
Cockbain finally departed, caught at deep cover by Cook off Bopara, who then claimed the wicket of Howell, caught at short third man by Zaidi, to finish with 3 for 34. Finally Norwell went down the wicket to Zaidi and was stumped.