Amateur rider John Alexander Salmond Mackenzie-Grieve was at his most active during the 1963/64 National Hunt campaign. He rode the two-mile chaser High Dyke, owned and trained by Oliver Carter, in the first seven of the horse’s 17 races that season.
They began their association at Uttoxeter on September 5, 1963, finishing last of eight. High Dyke refused next time out at Ludlow 12 days later. They pulled up at Wincanton the following week but then finished fifth of ten there on October 10, followed by ninth of twelve finishers at Taunton nine days later. Their next assignment was at Nottingham on October 29, where they trailed in last of the seven finishers.
High Dyke and his enthusiastic amateur rider then achieved their best placing when finishing fourth, beaten 21 lengths, in a Folkestone selling chase on November 5, 1963. That, however, was the last occasion on which they competed together. Six other riders, some amateurs, some professionals, took the mount on High Dyke during the remainder of the season, none of whom succeeded in getting him placed.
Mr Mackenzie-Grieve had just one other mount that season, pulling up on novice hurdle Lucky Boy Boy at Wincanton on September 26, 1963, half an hour before he rode High Dyke in the third of their seven-race partnership.