The Port Vale McAlpine hoodoo looked like continuing after another poor first half for the Terriers which saw a free kick which put away comfortably by Marc Bridge-Wilkinson after just 7 minutes.
The Valiants were up for it throughout the first half and their work-rate and passing put Town into the shade.
The scoreboard was in danger of becoming more entertaining as members of the McAlpine crowd looked at the growing drama at Bloomfield Road where Blackpool were handing Bristol City a hammering.
It was only late in the first half that the first signs of attacking football were witnessed from the Terriers.
With little that could be called a genuine chance on goal throughout the first half the Terriers grabbed their big chance during a rare period of pressure when Chris Hay put in a super cross which evaded Sagi Burton and fell nicely for Delroy Facey who converted it past Goodlad.
It was Facey's first home goal in over a year and it seemed to ease the nerves.
With the scores level and the Bristol losing badly the Terriers took to the field with more confidence in the second half.
Brian Horton's men found it much harder to break down the Terriers and, apart from a howler by Nathan Clarke after 55 minutes, when a poor back header had Margetson scampering out of his goal to cover for him, did not look the overwhelming threat that they had in the first half.
In the event, Clarke did his bit to save his blushes, coming back to protect Margetson's goal, but the Terriers were generally secure at the back.
Lou Macari had been urged to bring on Andy Booth in the first half and he did make an appearance in the second half, replacing Chris Hay, and he made his usual inroads into the Port Vale defence.
Booth himself scored the winner from close range when he tucked away a far post header drifted in by Leon Knight, who was devastating on the right wing.
Knight had linked up superbly on the right with Jenkins and the Terriers held their nerve to join in with the party that had already started around the McAlpine by the time the final whistle had gone.
The win, combined with Bristol City's defeat, had guaranteed the Terriers a play-off place. The question was, who would Town be playing?
Read Mel Booth's match report in the Examiner on Monday. Have your say on the match and Town's play-off chances in the messageboard below. Please leave your full name and location if you would like your comment to be considered for publication in the Examiner.
Town (4-4-2): Margetson, Jenkins, Gray, Clarke, G Evans, Thorrington, Heary, Irons, Hay (Booth 56), Knight, Facey
Subs not used: P Evans, Ifil, Moses, Delaney
Scorers: Facey 42, Booth 64
Port Vale (3-4-3): Goodlad, Carragher, McClare, Burton, Brisco (Armstrong 74), Cummins, Brooker, McPhee, Bridge-Wilkinson, Ingram, Burns (Donelly 46)
Subs not used: Delaney, Dodd, Paynter
Scorer: Bridge-Wilkinson 7
Referee: Mick Fletcher (Wolverley)
Attendance: 12,270 (434 Away Fans)
Match facts follow on subsequent pages
91 mins: Andy Booth ran the ball down to the corner flag.
90 mins: Town were still holding onto their lead.
88 mins: Blackpool 5 - 1 Bristol City.
87 mins: Town were playing deep and allowing Port Vale plenty of possession.
86 mins: Irons' free kick was headed upwards by Booth and then cleared by Burton.
85 mins: A blatant trip by Donelly brought Knight crashing to the floor after he looked like surging past the hapless Port Vale player.
84 mins: Port Vale were coming forward but were ineffectual as Town held firm.
82 mins: Town were comfortable as parts of the McAlpine crowd decided to form a conga - celebrating a win, and the playoffs, somewhat early.
80 mins: Thorrington's through ball for Facey was deemed offside.
78 mins: Knight tried to claim a penalty after he lost Irons' corner.
75 mins: Thorrington slipped as he shot in the Port Vale area. Cardiff 2 - 1 Notts County.
69 mins: Town were much more confident with Booth on the pitch and Knight linking so well with Jenkins.
64 mins: Andy Booth finished at the back post with aplomb from Knight's super cross after he was fed by Jenkins. A great header!
61 mins: Gray's flicked header was just over the bar.
58 mins: Burton's header took Knight's cross away from Facey. Booth was already putting himself about again as Knight and Jenkins' partnership clicked.
56 mins: Andy Booth came on for Chris Hay as Town went for a win. Thorrington switched to the left and Knight went to the right flank to link up again with Steve Jenkins.
55 mins: A shocking back header by Clarke was palmed away from a Port Vale attacker by Margetson who rushed out of his goal to save the day. Clarke made amends by retreating to the line to complete the clearance.
54 mins: Leon Knight's header across the face of goal was just wide after Jenkins' curling cross fell nicely for him!
53 mins: Blackpool 5 - 0 Bristol City. City were down and out at Bloomfield Road.
50 mins: Cardiff 1-1 Notts County. Town had an incentive to win to get a home second leg.
49 mins: Brooker escaped Gray to get to the long ball and shoot.
48 mins: Facey chased between Carragher and Goodlad but he had too much space to make up.
47 mins: Evans intercepted well but Brisco took him down with a rough challenge.
46 mins: Paul Donelly was on for Liam Burns as Town looked to capitalise on Bristol City's misfortune at Blackpool.
Marc Bridge-Wilkinson caught the Terriers cold with a great 7th minute free kick which rewarded a superb opening period for the Valiants. Port Vale had done their homework and Town were made to look very ordinary by Brian Horton's men for most of the first half. The Terriers had so few chances on goal that it was almost a surprise when Delroy Facey's equaliser on 42 minutes arrived during a rare period of Town pressure.
46 mins: Knight leaped to reach a cross for the header but couldn't direct it. Kenny Irons was better placed to take the ball as Town attacked effectively. Knight crossed from the right for Gray but the Town defender was penalised for climbing on Burton.
45 mins: Town were much improved after the goal but Port Vale continued to press despite going behind. Bridge-Wilkinson's shot trickled into Margetson's grasp. 3 minutes of added time were indicated.
42 mins: Delroy Facey hit his first home goal for over a year with an equaliser from Chris Hay's excellent whipped in cross. Sagi Burton missed the interception and Town fans celebrated the well-timed goal as the visitors looked at each other.
41 mins: Evans' long ball was too far in front for Facey to reach.
37 mins: Blackpool 4 - 0 Bristol City. Town were giving the ball away too cheaply, and the front men were isolated and having to drop deep to get a touch of the ball.
36 mins: Matt Carragher felled Leon Knight with a scything tackle. Knight's cross was repelled with Clarke and Gray waiting in the area.
33 mins: Blackpool 3 - 0 Bristol City. Stoke 1 -0 Wrexham. The crowd were baying for Andy Booth as Town continued to underperform.
32 mins: Thorrington's corner was caught by Goodlad who spaeked another attack with Brisco but Heary cleared.
30 mins: Heary belted high and wide when presented with a clearance.
29 mins: Town were hitting long, hopeful balls upfront for Leon Knight. Knight helped Hay win a corner with a lob into the box which was cleared.
28 mins: Knigth edged round Cummins and looked for a shooting position but his markers pushed him out wide.
27 mins: McClare belted the ball into the Kilner Bank after Knight and Irons got crowded out by Port Vale defenders.
26 mins: Carragher intercepted a Knight pass for Thorrington.
25 mins: Brooker was a danger and almost got past Gray as frustration began to set in at the McAlpine.
20 mins: Town were playing very poorly but the crowd were aware of the scores around the country and urged their team on. Thorrington's cross was intercepted - he was offside moments later as Town tried to prise an opening in the Vale defence.
15 mins: Blackpool 2 - 0 Bristol City - but Town were under the cosh from Bridge-Wilkinson who was thwarted by a back-tracking John Thorrington as the Valiants carved open the Town defence again.
13 mins: Port Vale were in fine form, first to the ball and generally more up for it than the Terriers.
12 mins: Cardiff City 0 - 1 Notts County - Mixed news for Town.
11 mins: Blackpool 1 - 0 Bristol City -- Good news for the Terriers.
10 mins: Town were struggling to cope with the extra attacking Valiants who had clearly come to enjoy themselves at the McAlpine.
7 mins: Marc Bridge-Wilkinson clipped the ball over the wall and into the back of the net past a watching Margetson direct from a free kick!
4 mins: Knight's run and through ball for Facey was too heavy after Thorrington had put him through. The visitors were in attacking mood.
2 mins: Very few Port Vale fans had travelled to see them start against Town. Brisco's shot was weak.
Lou Macari named an unchanged side to face Port Vale as they sought to seal their play-off place. Leon Knight was playing in his last match before a 3 match ban. Knight was hoping that this wouldn't be his last match, as he would be available for a play-off final in Cardiff if Town got there.