Hartley suffered a rare defeat in the win/lose format but bagged eight bonus points against Beckenham.
With second place Bickley defeating Bexley, Hartley now just require five points to be certain of the title. They entertain Lordswood at Culvey Close next Saturday and it hard to believe there will be not be big celebrations after the game.
Alex Blake hit a sparkling 144 after Beckenham chose to bat at Hartley. Will MacVicar chipped in with 44 as Beckenham set the home side a total of 288 to chase. In such a high score, James Thompson returned the excellent figures of 5-24.
In reply only James Hockley with 84 made a major contribution in the Hartley chase, and with Will MacVicar taking 4-31, Hartley ended on 204 for nine, resulting in a win for Beckenham by 84 runs.
Bickley Park have not given up the chase and they took the maximum 18 points as they visited Bexley.
The home side elected to bat but soon found themselves in trouble due to a fiery spell of 5-41 from Barry Hooper, only Maruf Chowdhury with 37 saving Bexley from a total disaster.
Adam Riley and Henry Pickering both scored 29 in the lower order to steer Bexley to a perhaps defendable total of 156 with the wicket offering some assistance to the bowlers.
Bickley lost four wickets for 88, but Dan Magin provided the innings of the match with an invaluable 68 and Bickley got home with four wickets in hand.
Skipper James Buterfill steered his Bromley side home with a vital unbeaten 33 in a low scoring match at Sevenoaks Vine. Electing to bat first, the home side lost wickets at regular intervals, only Oliver Durell 33 and Ollie Howick 32 reaching the thirties.
Wayne Morgan and Dominic Reed took three wickets apiece as they dismissed the Vine for 135 in the 39th over.
Bromley found batting no easier and without Butterfill's knock may not have reached their target. They did so with eight down, Karl Pearson the pick of the Vine bowlers with 3-25.
Sibton Park invited their visitors Lordswood to bat, a decision they may have rued when Fabian Cowdrey scored 68, Lyndon Lockhart 69 and Shaun Piesley 50 to build Lordswood total to a sizeable 278 for eight in their 50 overs.
In reply, Sibton lost wickets at regular intervals and were bowled out for just 159, Ben Allon top scoring with 44. Adeel Hussein took 4-40 to help his team to a comfortable victory by 119 runs.
There will be an exciting clash at Sevenoaks Vine next Saturday as they entertain Sibton Park, a match which could decide one of the relegation places.
In the final match of the day, Blackheath travelled to Whitstable and secured 18 points, winning by three wickets. Whitstable set the South-East London Club 161 to chase.
The home side made Blackheath work hard for victory, taking seven wickets, but their efforts were in vain as their visitors got home.