Denly led the carnage with 127 from 66 balls, including 11 fours and seven sixes, beating his own Kent record score of 116. The stand with Bell-Drummond, who was unbeaten at the end on 80, was the third highest for any wicket in the history of the competition.
It also beat the 163, a Kent record for any wicket at the time, the same two batsmen put on earlier in the season against Surrey at the Oval.
However, they were run close by the north Thames team, for whom Varun Chopra hit a career-best T20 114, his second of the season. His 58-ball innings included nine sixes and six fours. When he was out in the 18th over, Essex were 29 runs short with two overs to go, and they finished 11 runs adrift.
Kent now know that a third victory in a row on Friday night against Surrey at Canterbury will take them through to the last eight. Essex also require a win at Hove against Sussex to stand any chance of making the top four in the ultra-tight south group.
For Essex, only Mohammad Amir, who finally removed Denly in the penultimate over, returned decent bowling figures – his four overs cost a comparatively parsimonious 20. Of Essex’s seven bowlers, only Ravi Bopara went for less than 10 an over. Calum Haggett conceded just 18 in his four overs in Essex’s reply.
The start of play was delayed for 20 minutes while the air ambulance landed on the outfield to attend to a steward who had suffered a suspected heart attack.
Put in, Denly started as he meant to go on, contributing 37 of Kent’s first fifty runs including sixes over cow and long-leg off Jamie Porter and Paul Walter respectively. The former Middlesex opener reached the 23rd T20 half-century of his career from the 27th ball he faced.
Denly’s third six came from a free hit after an inadvertent beamer from Walter, the ball being lost as it sailed out of the ground over midwicket. A fourth cleared the ropes in the same vicinity in an over that went for 22 runs and took Kent into three figures in 12 overs.
Bell-Drummond had played second fiddle to his older partner, but a six off Simon Harmer took him to 37 and past the previous first-wicket partnership record of 119 for Kent against Essex in the format.
A swept four off Ryan ten Doeschate took Bell-Drummond to his fifty from 35 balls, and he had a second six to his name in the same over for good measure.
Denly reached his second century of the campaign with a boundary past mid-off. It had taken him 54 balls and contained 10 fours and a fifth six the ball before, hit straight off Zaidi. Another six took Denly to the highest of his three T20 centuries.
There was drama when the world record was broken: it looked at first as if Denly had gone on 119 to a catch on the long-leg boundary by Callum Taylor. But the fielder admitted he trod on the rope and Denly was not only reprieved, but credited with his seventh six.
He was finally out in the 19th over when he went for another big hit against Amir and was caught behind by James Foster. Kent lost a second wicket in the final over when Sam Billings was caught behind to give Walter his 15th wicket of the season, but at a personal cost of 65 runs on the night.
Essex went off like an express train in reply. By the end of the powerplay overs, they were 94 without loss and Chopra had reached his half-century from 19 balls. Mitchell Claydon felt the force in the sixth over when Chopra hit him for three successive sixes followed by three fours to move Essex from 64 to 94 in six balls.
Chopra had already hammered two sixes before that in the previous over from Claydon, whose first two overs went for 46. Sixes number six and seven came off successive balls from Imran Qayyum over long leg and then straighter.
Having put on 118 for the first wicket in nine overs, Dan Lawrence departed for a 22-ball 41, with one six, bowled by Calum Haggett. But at the halfway point, Essex needed 95 from 10 overs; incredibly, they were 34 runs ahead of the Kent total at the same stage of their innings.
They lost Bopara on 138, caught sweeping at Qayyum at short fine leg, as the brakes were applied to the Essex charge. Only 37 runs were scored in the six middle overs from the ninth to 14th and the pressure got to Zaidi who holed out to deep square leg in Darren Stevens’s first over.
A straight six off Neesham, his eighth, took Chopra to his century from 52 balls with six fours. With 39 needed off 18 balls, Chopra carted Neesham for six over midwicket before exiting two balls later, caught in the covers.
Ten Doeschate chipped a six over square leg off the last ball of the 19th over to leave Essex needing 16 from the last six balls. The captain went to the second ball, caught at deep cover by Qayyum, and Adam Milne tied up Paul Walter and James Foster in the final four balls.
Kent centurion Joe Denly was delighted and surprised to be given a standing ovation by the Chelmsford crowd after his record 127.
He said: “It’s probably one of the most hostile places to come. But I got a very special feeling walking off with 127 to my name and to have everyone standing up and applauding was a great moment.
“I’m delighted with my partnership with Daniel at the top. We work well together and run pretty well. To get a world record is something very special. I’m delighted for Daniel as well. It was close in the end but I thought our bowlers came back and held their nerve and managed to get the win that sets it up nicely for tomorrow.”
Denly was full of praise for seamer Calum Haggett, whose four overs went for just 18. “He was sensational in those middle overs and probably turned the game for us there. He has outbowled one of the best bowlers in the world in Mohammad Amir. Hopefully he takes a lot from it – and same again tomorrow against Surrey.
“After tonight we’re really excited for tomorrow. We’ll have a big crowd behind us and it’ll be a special night.”
Essex’s Varun Chopra said: “It was probably another one good for the spectator, plenty of runs and sixes, but another close one we’re the wrong side of. It’s another slightly sour one to take, but we’ve got to bounce back tomorrow and hopefully get two points and I guess hope a few results go our way. If thing work in our favour we can still go through.
“We got off to a lovely start with Dan Lawrence playing nicely and freely at the other end. I had that one good over and we were in a good position. Chasing a total like that you always need to keep going and we probably didn’t find that partnership towards the end to see us over the line.
“I think by the middle overs they had worked out the wicket a bit and we lost a couple of wickets as well. We were up with the rate the whole time. It was probably just the 17th over where he [Mitchell Claydon] bowled a good over, just six singles, that was the over that really put us under. I got out and it is difficult for players to come in and score at 13 an over from ball one.
“We won’t dwell on it too long. It was a pretty disappointing performance for us in the field and with the ball, and we can’t be proud of it. But Mohammad Amir was outstanding and showed his class as he’s done all tournament – his overs went for 20, while everyone else was going for 12s and 15s an over.”
Chopra now has more than 400 runs in T20 cricket this season. He said: “I’ve been given the freedom at the top of the order to express myself and hit shots. Previously I’ve either been captain or my role in the side has been to bat through a little bit more. I guess I’m really enjoying being told just to go and hit the team as hard as I can. I wonder what I’ve been doing for the last 12-15 years! It’s good fun at the moment, but things can always change, particularly in T20. It’s fun to play, but when you lose the rhythm it can be horrible.”