Bradley smashed 108 from just 65 balls, including 14 fours and four sixes, with opener Heslehurst unbeaten on 106 from 128 deliveries, including 12 fours, the pair sharing a brilliant second-wicket stand of 158.
Heslehurst and Joe Brotherton (61no from 37 balls) also shared a century stand for the fourth wicket as Ganton racked up a massive 338-4.
Seamer slumped to 125 all out in reply as Ganton cantered to victory.
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Snainton held on for a five-run win at Cayton 2nds in thrilling encounter.
An exceedingly good knock of 97 from Mike Kipling, allied to 41 from fellow opener Tom Poor (41) gave Snainton the upper hand, an opening stand of 112 laying the foundations for the visitors' 222-5.
Kipling also put on 71 for the fifth wicket with Matthew Davies (36no), Jake Seastron bagging 3-24.
Stalwart Simon Glave (37) and Lee Pettitt (58) kept Cayton in contention during their run-chase, but, despite a defiant 36no from Kieran Glave, Snainton's bowlers pegged the hosts back to 217-8, Kipling capping a superb all-round show with 3-63 after fine spells by Ben Norman (2-34) and Luke Calvert (2-33).
Another game that went down to the wire saw Settrington hang on for a six-run success in a high-scoring contest at Glaisdale.
Skipper Ben Corner led by example with a sparkling 83 for the visitors, with fine performances from James Richardson (48), Stephen Beal (40), Jamie Rounthwaite (26) and Rob Harrison (26no) steering Settrington to an imposing 271-8, Graham Featherstone taking three wickets for the home side.
The hosts were soon in trouble at 12-2, but a third-wicket stand of 127 between William Burtt (69) and Jack Allanson (57) got Glaisdale back on track, skipper Tom Wardell adding a solid 52, but fine bowling from Matthew Midgley (4-69) pegged the hosts back to 265-8.
Second-placed Mulgrave 2nds secured a 53-run win at Wykeham 2nds.
Skipper Simon Kipling's 34, allied to Charlie Mckernon's 32, with cameos from Kieran Spenceley (22) and Oliver Stabler (22) guided the hosts to 188-9.
Fine bowling from Ian Spence (4-29) and Scott Wardman (3-25) helped keep Wykeham in the game.
The hosts never really looked like reaching their target despite a battling 66 from David Stockhill as they were dismissed for 135, Pete Stentiford bagging 4-17 and Ben Duell 3-31.
Third-placed Nawton Grange 2nds won by 49 runs at home to Scalby 2nds.
Nathan Barber's 3-13, along with two wickets each for Tom Hendry and Adrian Hollingsworth put Scalby in a good position as they dismissed Grange for 152.
Skipper Darren Smith hit a crucial 29 down the order for the hosts, George and Richard Bentley struck 20 apiece.
George Bentley was the all-round star as he snapped up a match-winning 5-9 to send Scalby crashing to 103 all out, Theo Slade top-scoring with 22 for the visitors.
Flamborough continued their 100% start to the season with a 10-wicket home win against second-placed Ravenscar.
Adam Graham and Ciaran Bartram, with 20 apiece, along with 17s from Robin Coulson and skipper Shaun Bayes, were the only batsmen to get going for Ravenscar, who slipped to 115 all out, Jack Carradice-Clarkson and Luke Dixon bagging three wickets apiece.
Openers Dixon and Mark Abram wrapped up the win thanks to an unbeaten stand of 119 in 21.3 overs
Third-placed Scarborough Rugby Club triumphed by seven wickets at Folkton & Flixton 3rds.
Mark Kelly took an excellent 4-15 and William Kelly 3-31 as Flixton were skittled for 110 in 31 overs, Evan Chapman top-scoring with 26.
Marcus Edwards' 55, allied to 27no from fellow opener Rob Hazledine, secured the win for Rugby Club with ease.
Greig Cowie's excellent 109 helped Grosmont storm to a 241-run home success against eight-man Wold Newton.
Cowie and fellow opener Anthony Clarkson, with an impressive 70, helped the hosts rack up a huge 296-3, with Arran Liddle hitting 42.
Newton then crumbled to 55 all out, Clarkson bagging 2-6 and Carl Oliver 2-4.
Muston earned their first win of the season, coasting to a 73-run triumph at home to eight-man Great Habton 2nds.
Opener Kyle Orange's 65 from 60 balls, including 10 fours and two sixes, proved to be crucial as 10-man Muston were all out for 145 in 26.3 overs, Jonathon Atkinson adding 31 down the order.
Alfie Stephenson bagged 3-31 for Habton, with two wickets apiece from Jack Campbell-Carter, James Spencer and Vernon Smith.
The depleted visitors were then skittled for 72, Dave Meer taking 3-22 and two wickets each for Mathew Hall-Atkinson and Orange.
Filey 2nds conceded their game at Goathland.
Division Four leaders Pickering 3rds dug deep for their one-wicket win at Forge Valley 2nds.
Dan Boyes' 53, alongside 27 from veteran Pete Wannop steered Valley to 145-7, skipper Steve Boyes adding 21.
Macauley Gibson's stunning unbeaten 83 in reply proved crucial as Abbie Boyes' excellent 4-29 gave Valley a sniff of victory, Gibson and number 11 Jared Gill guiding the 10-man Pikes home.
Dave Williamson's excellent unbeaten 129 guided 10-man Staxton to a three-wicket win at Scarborough 3rds.
Ben Crick's brilliant 103 looked to have put the hosts in pole position after posting 217-9, but Scarborough slipped from 179-1 to 216-9 as Craig Hill and Mark Dove scooped three wickets each.
Staxton slipped to 26-2, but a stand of 116 runs for the third wicket between Williamson and Paul Russell (39) got them back on track, but then Jonathon Crick's 4-43 gave Scarborough a sniff of victory only for Williamson to wrap up the win.
Second-placed Malton & Old Malton 3rds won by four wickets at home to Bridlington 3rds.
Tom Pinder took three wickets from just four balls without conceding a run to mop up the Brid tail as the visitors were dismissed for 93, Thomas Shephard top-scoring with 28.
Opener Swaminathan Thiagarajan then laid the foundations with 44 in reply, but a stunning spell of 5-15 from Shephard sent Malton crashing from 70-0 to 79-6, but the home side held their nerve with Gareth Driver (5no) and Pinder (5no) steering them home.
Sherburn 2nds cruised to an eight-wicket win at home to Brompton 2nds.
Jordan Farrow's five-wicket haul helped dismiss 10-man Brompton for 73 runs in 23 overs, Phil Holden hitting 26.
Connor Miles' 30 steered Sherburn to victory with 77-2 in 15.2 overs.
Wykeham 3rds moved up to third in Division Five after a 57-run home win against Scalby 3rds.
Opener Andy Shepherdson's 47, allied to 24 from Robin Shepherdson and Ian Thompson's 21no steered the hosts to 165-9, Will Holborn on top form with 4-27 and Steve Marson scooping 3-31 to keep Scalby in the game.
Opener Josh Lowe struck an impressive 63 to keep Scalby in with a shout but top bowling from Harry Amstell (3-12) dismissed the visitors for 108, Thompson taking two wickets to complete a fine all-round display.
Babu Matthew's brilliant 80 helped Forge Valley 3rds earn a 90-run success at home to Nawton Grange 2nds.
Liam Wood took 3-21 as Valley were all out for 187 in 39.2 overs.
Santal George's stunning spell of 5-28 in nine overs then helped Valley skittle Grange for 97 runs, Wood top-scoring with 27.
Ravenscar 2nds are top of the division after Thornton Dale 2nds conceded their match.