More than 2,000 turned up at Sixfields and were able to enjoy the action - if not the outcome of a frustrating and scarcely believable afternoon - from their seats in the west stand.
The sun was shining, and the beers were flowing as, for once, the fans were able to take their drinks to their seats as the normal match day rules on alcohol didn't apply.
The atmosphere was crackling before the game, and the roar that greeted the players as they emerged from a tunnel 230 miles away was as if they were on the pitch in front of them, just a few yards away.
Such is the respect shown by football fans, the minute's silence observed at Barrow for former Bluebirds striker Neil Campbell was also impeccably observed at Sixfields, which was a nice moment.
By 20 minutes in, the atmosphere was a party one as two goals from Sam Hoskins and one from Fraser Horsfall had the Cobblers in control at 3-0 up.
Chants or 'we are going up' rang out from the Town fans at Sixfields, but there was always that nagging feeling at the back of everybody's mind that Bristol Rovers could still pip the Cobblers with a load of goals against already-relegated Scunthorpe United.
Sixfields silence greeted Josh Kay's header to make it 3-1, but with Rovers only winning 2-0 at the Memorial Stadium at that time, it was still very much advantage Cobblers.
So the atmosphere was still pretty upbeat and relaxed, but as the Cobblers struggled to get going in the second half, and the news kept coming through of further goals flying into the Scunthorpe net in Bristol, the tension grew... and grew...and grew.
Rovers went 5-0, 6-0 up and then 7-0 and there was an air disbelief around Sixfields as it really sunk in that the Cobblers were on the brink of missing out on promotion on the amount of goals scored over the season.
The goal difference of both teams was identical at plus-22, but the Gas had scored 11 more goals over 46 games…
The crowd roared their on-screen heroes on to try and score the fourth goal at Barrow that would get them promoted... but despite two good chances for Hoskins, it never came.
A pitch invasion at the Memorial Stadium had meant their game was delayed once the Cobblers match was finished.
Plenty of fans headed straight for the exits, but about a third of the fans inside Sixfields waited and listened to the commentary from the Memorial Stadium being broadcast over the speakers.
They were hoping and praying Scunthorpe might, out of somewhere, conjur a goal that would change everything, but of course they didn't and the Town fans drifted away in disappointed silence.
It was certainly a tough one to take, but everybody at the club has to now lift themselves and get ready for the play-offs - and Sixfields will no doubt be full and rocking for the second-leg against Mansfield Town on May 18.
The club certainly appreciated the support for the team back in Northampton, and on Sunday tried to lift the mood with a message on social media.
"Thank you to everyone who came to Sixfields for the beamback," it read.
"Not the outcome we wanted, but we move on to the play-offs together, proud of the connection between club and the supporters that has grown and grown this season."
Now for those play-offs…
All pictures by Kirsty Edmonds