In front of a sell-out attendance of 5,621, referee Damian Hancock’s decision to award the spot kick looked harsh on a St Pat’s side richly deserving of a share of the points as the flight of the ball brought it into contact with skipper Conor Kenna.
But Quigley made no mistake with a cool finish that bridged a 35-year gap and brought hundreds of delirious fans on to the pitch in a glorious eruption of jubilation.
Sligo boss Ian Baraclough said he: “tried to keep calm” when Mark stepped up to the penalty.
“35 years is too long without a league title coming to the town, but I’m so proud of these footballers and we enjoy working together. When the chips were down and our backs to the wall, we really dug in.
“The football has been magnificent and it’s a testament to all the hard work put in by the players and staff.”
Baraclough’s 78-year-old father Ron was also watching from the stands as his son masterminded a brilliant victory.
Sligo got a dream start with Raffaele Cretaro firing low into the bottom of Barry Murphy’s net in the 20th minute and the celebrations had hardly died down when he headed a Ross Gaynor corner past the Saints keeper.
With 23 minutes on the clock the Showgrounds was rocking and Quigley ballooned the ball over the visitors bar from 30 yards.
But the Saints pulled a goal back when Christy Fagan rattled Gary Rogers’ net seven minutes into the second half, and suddenly Sligo found themselves stretched.
Chris Forrester squared the match on 59 minutes drilling the ball past Rogers from 35 yards and substitute Anthony Flood went close for the visitors after 83 minutes but all of their good work in the half was undone when Quigley scored. “The best team wins the league,” said Quigley afterwards. Hard to disagree.
SLIGO ROVERS: G Rogers; J Henderson (Cawley 53), G Peers, J McGuinness, R Gaynor (Dillon 75); L Lynch, D Ventre, J Ndo (Buchanan 83); P Millien; M Quigley, R Cretaro.
ST PATRICK’S ATH: B Murphy; G O’Brien, C Kenna, K Browne, I Bermingham; J Chambers (Russell 69), J Carroll, G Bolger (Faherty ht); C Forrester, C Fagan, S O’Connor (Flood 78).
Referee: Damian Hancock (Cork).