Not quite... Michael Lowrie won the Scottish Under-21 title on 13 September at Powderhall (Edinburgh) which was part of the Scottish Individual Riders Championship, won by Scott Lamb, with James Grieves winning the Under-18 title.
The Junior Championship was held at Shawfield on 13 Oct 1991 (points scored carried into the final - I don't have the race times)
Heat 1: Grieves, Fraser Smith, Paul Taylor, Raymond Fosbury
Heat 2: Stuart Coleman, Wayne Park, Stuart Crome (retired), Stewart McDonald (fell excluded)
Heat 3: Coleman, Grieves, Fosbury, Crome
Heat 4: Smith, Park, Taylor (only 3 riders)
Final: Grieves, Coleman, Smith, Park (fell remounted)
As Grieves & Coleman both scored 8 points, a race-off was needed, which Grieves won.