In front of a paltry 2037 fans, player-manager Kernaghan superbly marshalled his defence through a tricky away match, despite Saints camping in the Clyde half for much of the game.
But in truth, Saints' lack of ideas in front of goal did just as much to aid Kernaghan's men.
"The fans wouldn't have enjoyed that one much", said Kernaghan, who left Saints last season before the Clark rot set in, moving first to Brechin City on a short-term deal and then to his present employers.
"Saints had most of the ball and we just tried to make sure they didn't get in behind us.
"St Johnstone are a good footballing side and try to control the game, but if we'd gone forward more often then Saints would have been able to score."
Billy Stark was disappointed with our players - showing a rare glimpse of criticism towards them - and feels that the squad is suffering from a chronic lack of self-belief.
"We can't expect to win every game but I thought we didn't handle that well today," Stark admitted.
"We started the game brightly again - but the players have to be stronger than they showed today.
"I really can't understand it - there's a fragility when we go into games. If they're going to do anything they need to get a little self-confidence.
"Confidence is everything in any sport. If we'd gone out and got the big win we should have had, then it might be a bit different.
"The players haven't let anyone down this season but they let themselves down today."
In typical gentleman style though, Kernaghan defended the Saints boss and pointed out the perils of First Division football, especially with Falkirk losing their unbeaten record at Arbroath.
"The title isn't lost in October," Kernaghan admitted.
"Saints lost last week but there's a long way to go and other teams will beat each other before the end of the season."