On a day when an early start proved beneficial – those off later had to cope with cooler conditions – McMullen carded a one-under-par 70 to finish a shot ahead of Caird Park’s Connor Good and George Burns from Williamwood.
McMullen, who cut his golfing teeth at Lochgelly but has since made Lundin his home club, birdied the first and was two-under for the round after 11 holes before finishing bogey-birdie-birdie.
Cook, a semi-finalist in the Scottish Boys at Murcar Links two years ago, mixed three birdies with three bogeys while Burns’ card contained an eagle – at the sixth – as well as two birdies and four bogeys.
Connor Syme finished fourth on 72, the two-times Scottish Schools’ champion from Dumfries & Galloway covering the last eight holes in two-under after earlier running up a double-bogey 7 at the sixth.
He wasn’t alone, though, in signing for that figure on a day when the Old Course Hotel-owned course showed some teeth. Ferguson, last year’s British Boys’ champion from Bearsden, had a triple-bogey 7 at the 17th in his 75 – it earned him fifth spot – while Bradley Neil, the world No 66 from Blairgowrie, had three 7s in a ten-over 81 that left him down in a tie for 26th.