But from the resulting goal kick downfield Forest caught Oldham cold, with a flick on header falling to Nigel Clough who passed the ball to Jemson, who ran into the box and fired left of the Latics keeper Rhodes.
Rhodes dived the wrong way to his right, but his feet blocked the ball, but Jemson was in to put away his effort at the 2nd time of asking and Nottingham Forest were 1-0 up with only 2 minutes of the 2nd half played.
Parker had a great chance to score in the 50th min when running at goal from a misdirected Oldham clearance from a throw in, forcing Rhodes to handle outside his area.
Jemson also had a chance to double his lead when he turned his marker Earl Barratt before running at goal, barging past Barlow and curling a shot to the keeper's right to force a save.
Forest seemed to sit back to invite the Oldham pressure on in a bid to catch them out on the break and also to preserve energy in the stifling heat.
Towards the end of the game Forest were playing for time and keeping the ball in the corner, as the heat and the intensity of the Oldham pressure took their toll, but they held on to secure the cup and defend it, repeating their feat when they did so in 1978 and 1979.