Stones dominated the first half but could not break the deadlock, foiled by the woodwork and by outstanding Beachboys keeper Luke Chambers.
Concord offered little threat, though they did hit the bar early in the second half with a Steve King header. It seemed, however, that the script had been written when Richard Jolly headed home a free-kick in the 63rd minute to give Stones the lead.
It was his 194th goal for the club in his 279th appearance and it looked as if he had given himself the chance to extend both totals before he retires at the end of the season.
Concord’s key forward Tony Stokes (pictured) had been unable to start the game after being taken ill on the journey but he entered the action in the 76th minute and the Beachboys began to apply serious pressure for the first time.
The game had just gone into its 90th minute when the men from Essex drew level. A shot from Leon Gordon was blocked on the line and an attempted clearance cannoned back into the net, apparently off a Stones defender although King was awarded the goal.
So that meant an extra half-hour and the winner came three minutes into the second period. It was another untidy affair, with a King effort coming back off a post and, as the home side failed to clear the ball, Stokes hooked it over the line.
Concord held out in reasonable comfort and at the final whistle Jolly slumped to the ground in despair, knowing that his career had been ended by Wealdstone’s second successive play-off semi-final exit.
The clubs’ previous meeting had ended on a somewhat sour note so it was good to see the Concord players gathering by the tunnel to applaud their opponents off the field.
Their task in Monday’s final will be a trip to Lowestoft after the Trawlerboys reached the final with a 1-0 home victory over a resilient East Thurrock side. Chris Henderson prodded in the 80th-minute winner, ending the prospect of an all-Essex final.
It will be Lowestoft’s third successive appearance in the final. They were beaten at Tonbridge and Hornchurch in the previous two but they will hope to go one better with home advantage.
Both games attracted four-figure crowds, with 1,182 watching at Lowestoft and 1,055 at Wealdstone.
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