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Ashford’s promotion hopes were ended by Horsham in Friday night’s play-off final.
They came from behind at Lancing's Culver Road and Sam Mott saved a penalty but it was the Hornets who lifted the trophy after scoring the winner in extra time.
Even if United had won, they would have been waiting on the results of two other play-off finals over the Bank Holiday weekend to discover their fate.
Only five of the seven play-off winners at Step 4 will go up this season, with points-per-game used to decide who misses out.
Ashford would have needed Brighouse and Cinderford - two teams who couldn’t go up anyway - to both win their finals, but in the end it was all academic.
The visitors were unchanged from their dramatic semi-final win at Hastings, which meant Lee Prescott had to settle for a place on the bench on his return from a three-match suspension.
Play-off finals are often tight affairs but even by those standards, most of the first half was a complete non-event in foul conditions as heavy rain swept across the ground.
There was concern for Danny Parish inside five minutes when the Ashford striker took a whack to his calf but after fairly lengthy treatment, he was able to carry on.
At the other end, a deflected effort from Chris Smith ran through for Mott as Horsham began to enjoy a decent spell of territory and possession.
Rob O'Toole lashed a shot across the face of goal and Ashford survived a series of corners with their centre-halves standing up well.
Mott had to be out smartly to save at Smith's feet and Jay May was spoken to by referee Joel Mannix after leaving Dylan Merchant in a heap after they challenged for an high ball on halfway.
The final was meandering towards the interval with very little happening when Horsham took the lead with a goal out of the blue. Ashford failed to clear a free-kick from their right and Goerge Hayward lashed a brilliant shot high beyond Mott's left hand from just outside the D of the penalty area.
United, to their credit, responded well to going behind.
Full-back Jerald Aboagye took the fight to Horsham with a couple of strong runs down the right, his first cross glanced on by Parish although no-one in a yellow shirt was able to apply the crucial touch at the back post.
Parish's connection from Aboagye's next cross was better and he forced a good save from Josh Pelling, with the rebound running kindly for May. Everyone inside expected the net to bulge but May rammed the ball against the crossbar and it bounced down on the wrong side of the goal line from a United point of view.
However, deep in added time at the end of the half, Josh Wisson was caught by an outstretched leg and when Mr Mannix pointed to the penalty spot, Corne's low shot squirmed inside the post despite Pelling getting a strong hand to the ball.
Ashford, clearly buoyed by the goal, started the second half much the brighter of the two sides.
May rose well to meet a high cross from the right and Bode Anidugbe's energy in midfield started to get the Nuts & Bolts moving forward.
However, it needed some brave goalkeeping from Mott to deny Horsham a second goal as he spread himself at the feet of the onrushing Smith, who was beyond the last defender.
John Coker was inches away from putting Ashford in front when the home side didn't clear Corne's deep left-wing corner and a defensive breakdown in communication almost allowed May to play in Parish.
United's set-pieces were giving Horsham problems and May sent a free header over the bar as frustration among the home crowd grew.
Ashford were starting to get control in midfield but Horsham had a golden opportunity to retake the lead when Coker tugged back Rob O'Toole in the area. O'Toole took the penalty himself but Mott guessed right, diving to his left and making a terrific save.
Coker made a crucial challenge to block Lee Harding's shot when he ran onto Kieran Lavery's pass but play quickly switched to the other end, with Laurent Mendy driving inside from the left and powering a shot wide.
The end of the 90 minutes were absolutely frantic with both sides going close to a winner. Anidugbe forced a save from Pelling and Parish fired a low shot just wide after Toby Ajala had led a rapid counter-attack, although it needed a match-saving tackle from Aboagye to deny Lavery after some sloppy defending had let him into the box.
Horsham piled on the pressure in four added minutes and had a huge penalty shout for handball waved away as the Nuts & Bolts dug deep to force extra time for the second time in five days.
Anidugbe floated a shot over at the start of extra time after May and Corne had done well to create an opportunity 25 yards out.
There was a nervous hush on three sides of the ground now but the Ashford fans kept singing behind Mott's goal as their side battled on and on.
Mott pulled off a fine double save to first keep out Lavery's free-kick and then stop Merchant heading home the rebound.
Ashford, who were now being pushed to their limit, threw bodies in front of another Lavery shot although when Anidugbe played in Ajala at the other end, he forced a smart block from Pelling.
Tommy Warrilow made a triple substitution during the change of ends and two of the players he sent on almost combined straight away. But after Parish had run at the Horsham defence and fed Trey Williams, his pass was slashed wastefully wide of the near post by Jake McIntyre.
That miss looked even more costly a minute later when Merchant rose highest in a crowded penalty area to head home Joey Taylor's free-kick from the right.
Horsham: Pelling, Metcalf, Sparks, Brivio, Shelley, Merchant, Richardson-Brown (Taylor 106mins), Hayward, O'Toole, Smith (Lavery 70mins), Harding (Lovegrove 117mins). Subs not used: Hyde, Mant.
Ashford: Mott, Aboagye (Williams 106mins), Mendy, Wisson, Coker (Prescott 106mins), Kamara, Corne, Anidugbe, Parish, May (McIntyre 106mins), Ajala. Subs not used: Hook, Munyama.
Attendance: 880.