His sweet strike pulled the Easter Road side back into the game and gave them the lift needed to move, temporarily, top of the Premiership standings.
It also helped shine a spotlight on a player who only a couple of weeks ago had been deemed surplus to requirements by the Edinburgh outfit.
Thrilled by a second-half performance that gave his side fresh impetus and creative nous, Hibs boss Jack Ross says no one was pushing playmaker Allan out the door during the most recent transfer window, but the talismanic midfielder was a makeweight in a deal that had been agreed to bring Buddies’ Jamie McGrath to the capital. Had the clubs not run out of time when processing the paperwork on the final day of the window, Allan could have been representing St Mirren on Saturday.
Instead, he lit the fuse under a 20-minute spell at the start of the second half, during which the home side battled back from a flat first 45 minutes, producing two goals to overhaul their guests’ deserved opener and edge ahead.
The fact they couldn’t hang onto that lead said as much about the positive play and industry of Jim Goodwin’s men as it did about Hibs’ limitations on the day.
With so much talk about Hibs’ attacking options or lack thereof, thanks to the way the transfer window ended and James Scott’s illness and Christian Doidge’s injury, it was the St Mirren frontline who caught the eye, with Eammon Brophy a standout and Curtis Main perhaps the kind of player Hibs needed to recruit when Doidge was diagnosed as a long-term absentee.
Brophy grabbed the 42nd-minute opener with a near-post finish he will relish, but Hibs keeper Matt Macey will regret.
But 12 minutes after the break Allan provided guile and great vision. After two shots had been blocked, he took a second and instead of simply lashing a third effort he displayed the composure, the awareness and the ability to float a ball out of the melee and into McGinn’s path. The right-back finished first time.
“I was happy to have found someone who can actually put away one of my passes,” said Allan. “You can play those passes all day and, if somebody doesn’t score, nobody remembers them. So kudos to Paul McGinn because it was some finish.
“You’re just happy to have come on and been influential.”
But he admitted that clear-the-air talks were needed after the St Mirren swap fell through.
“Oh we definitely spoke about it afterwards! But, for me, it was about training hard and then, when getting on the park and reminding people what I can do.
“I can definitely play 90 minutes but the manager picks the team.“
Martin Boyle added Hibs’ second in the 61st minute after Ryan Porteous earned a penalty, but St Mirren weren’t done and came back at them with a late equaliser from Joe Shaughnessy.
Allan came close to a winner, though, but was denied when his deflected shot skimmed off the outside of the post and, just like deadline day, both sides had to be satisfied with what they already had.