Kent 287 for 8 (Leaning 137*, Compton 65, Webster 3-38) beat Essex 227 (Buttleman 50*, Khushi 50) by 60 runs
Will Buttleman made an unbeaten 50 and Feroze Khushi hit exactly 50 for Essex but the visitors lost wickets too frequently to mount a credible run chase and they were all out for 227, with 5.1 overs remaining.
Grant Stewart, Hamid Qadri and Matt Parkinson all took two wickets for the Spitfires.
History was made at the Spitfire Ground on Sunday, where Joe and Jaydn became the first uncle and nephew to play since the modern club was formed in 1870, and the first since Fuller Pilch and his nephew William appeared together for the “Grand Old Kent XI” 41 times between 1838 and 1854.
In front of a crowd of 2400 Kent chose to bat, but for a third consecutive game they threw away a promising start, having been 130 for one at halfway.
With Daniel Bell-Drummond back on Hundred duty, Uncle Joe opened, but he was the first wicket to fall when he edged Aaron Beard behind for 17.
Compton and Leaning put on 98 for the second wicket, but after what by his standards was a fairly rapid half-century the former was caught behind off Beau Webster in the 25th.
Webster then bowled Alex Blake for one and Beard strangled Harry Finch down the leg side for seven.
Jaydn Denly joined Leaning to steer Kent past 200 but he was bowled for 37 attempting to sweep Webster and Kent’s hopes of passing 300 vanished in the 43rd over, when Aron Nijjar struck twice.
Grant Stewart was out first ball when he played on and Hamid Qadri had made just one when he chipped the bowler to Webster.
When Matt Quinn then drove Richards straight to Nijjar at mid-on four wickets had fallen for five runs in 10 balls, 250 looked a long way off and Leaning was in danger of running out of partners until Jas Singh came in and played the Jack Leach role. Smart running between the wickets saw Leaning to the brink of three figures, which he reached when he punched Beard for a single through mid-on and he then launched an assault in the last two overs.
The 29th, bowled by Ben Allison, went for 13 and a pivotal 27 then came of the 50th, with Leaning hitting Beard for three leg-side sixes and Singh ending on two not out after a match-turning unbeaten stand of 69 from 44 legitimate balls.
Essex were 33 without loss in reply when Luc Benkenstein was run out by Jaydn Denly chasing a second.
Quinn then nearly had Tom Westley caught behind for a duck and although the ball came lose as the diving Finch hit he ground, he was caught behind off Stewart for two in the next over, the seventh.
Webster came in and put some pressure back on the bowlers, but he was out for 26 from 25 balls when Jaydn Denly had him caught at long on by Blake.
The younger Denly then produced what was arguably the game’s champagne moment when he took a sensational diving catch to remove Khushi, who’d just reached 50 and was trying to hit Matt Parkinson through cow corner.
Hamid Qadri struck with only his fourth ball, when he had Noah Thain caught by Stewart at mid-off for 141, before claiming the key wicket of Charlie Allison, lbw for 44.
Parkinson trapped Ben Allison lbw for seven in the 38th and in the next over Beard went in the same fashion to Leaning for two.
Leaning then caught and bowled Jamal Richards with his next delivery and although Buttleman hit the hat-trick ball for six Kent sealed the win when Stewart had Nijjar caught by the sub fielder Nathan Gilchrist.
Kent remain in the hunt for a place for the knock-out stages, but will probably need to win at Hampshire on Tuesday and hope results elsewhere in Group A go their way.