THE unfathomable disparity between St Mirren’s league and cup form this season goes on. In despatching Welsh Premier League side The New Saints (TNS) to reach the Irn-Bru final, they recorded their tenth victory in 11 cup ties this season. In contrast they have won just two of their 23 Championship matches to perch precariously on the brink of relegation to League One. It is an anomaly that must have manager Jack Ross scratching his head trying to make sense of it all.

There was an element of Jekyll and Hyde about their performance over the 90 minutes here, too. Desperately poor in the first half and trailing to a Ryan Brobbel goal, Ross sent on Lewis Morgan at the break and St Mirren were a side revitalised, running in four goals and even able to afford the luxury of missing a penalty. TNS, who had former Motherwell and Ross County defender Steven Saunders sent off for a wild challenge on Stephen McGinn, tamely capitulated.

“In the first half we were a disgrace and I said that to the players at half-time,” admitted Ross. “I was so angry with them as it’s no reflection on how we do things. And the second half was - and that’s why we won the game.”

St Mirren now take on Dundee United in the final on either March 25 or 26, an apt reunion on the 30th anniversary of the sides’ meeting in the 1987 Scottish Cup final. United will start that game as favourites, although, given their rivals’ cup record this season, only the foolish or bold could write St Mirren off.

“Winning things in football doesn’t come round very often regardless of the competition and we believe we can go and do that,” added Ross. “We believed that before today’s game and nothing changes having got through to the final. The fact it’s two clubs of ours and Dundee United’s stature should help add to the attraction of it, 30 years on from the final in another competition.”

St Mirren were as good in the second half as they had been poor in the first. Morgan’s introduction made a notable difference and on the hour mark his side drew level. It was a terrific strike from McGinn as he accepted a lateral pass from Stelios Demetriou, advanced forward a couple of strides before unleashing a shot that sailed into the top corner.

Saunders’ red card four minutes later put the Welsh club up against it and St Mirren made them pay for their transgression from the resultant free kick. Stephen Mallan had put a first-half effort straight over the stand but he was far more accurate at the other end, bending his shot beyond the wall and into the far corner.

St Mirren were by now fully in their stride and should have scored their third after 78 minutes. Morgan’s cross into the box was stopped only by the hand of Scott Quigley and referee Keith Kennedy gave the penalty. John Sutton, though, could not take advantage, his kick easily saved by goalkeeper Paul Harrison.

Sutton would make amends, however, just a minute later as St Mirren went immediately back on the attack. Stelios fed Kyle Magennis who sidestepped a tackle before showing great composure to pick out the lurking Sutton who finished well.

All fight had gone out of TNS by this point and they conceded a weak fourth in the final minute, a short free kick from Mallan finding Rory Loy who drilled a low shot beyond Harrison to complete a positive afternoon for St Mirren. It was the cup after all.