As Swansea tried to cover all the angles with their defensive wall, Frain sent a thunderous shot into the top right-hand corner to send Town's 33,000 fans delirious.

The goal could not have come at a better time for Ian Atkins' side, with half-an-hour of extra time looking the most likely option from a lacklustre Third Division final.

Jan Molby's Swansea team had been unable to break through the Northampton defence despite having more of the play overall.

Not even Molby's experience could unlock a Northampton back four, marshalled superbly by skipper Ray Warburton.

Swansea almost went in front as early as the fifth minute when Carl Heggs sent a right-foot volley towards the top corner from 20 yards. But goalkeeper Andy Woodman twisted in mid-air to tip the ball over the bar.

Northampton then had the best chance of the first half to break the deadlock. Molby, who had tried in vain to calm a hectic midfield, was robbed in the centre circle by Neil Grayson.

The Northampton midfielder burst forward and laid the ball off for Sean Parrish. Although his shot beat Swansea keeper Roger Freestone it was cleared off the line by Christian Edwards.

The second half fared little better, with both sides restricted to long-range efforts.

The closest either came to scoring, before the dramatic last seconds, was in the 54th minute when Northampton's Christian Lee sent a header flashing inches wide.

Swansea produced a late spell of pressure but Atkins' side prevented them getting a clear shot on target.

Northampton, sensing they had one last throw of the dice to clinch a Second Division spot next season, launched a final flurry on the Swans goal.

Their efforts seemed to have come to nothing when Keith Walker brought down Parrish on the edge of the box.

But Frain had other ideas and, after his twice-taken free-kick had found the net, Wembley was a sea of mauve as the Northampton fans celebrated promotion.

Swansea never had the chance even to attempt to get back in the game as referee Heilbron blew the final whistle seconds after the restart.

Swansea player-manager Molby clearly felt unhappy with the County Durham official's decision to have the decisive free-kick retaken.

As his crestfallen troops lay distraught on the Wembley turf at the end, Molby was seen to have heated words with Heilbron in the centre circle. Molby was apparently protesting that the kick should never have been retaken after Coates had launched himself at the ball.

Swansea's player-manager then lead his troops towards their fans while Northampton climbed the famous steps to collect the trophy before beginning a lap of honour in front of their travelling army of supporters.