The hardest player he has ever seen, said Jim Telfer, and there are few more qualified to pass comment.
Armstrong was first capped as a 21-year-old against Australia in 1988, the first of his 44 appearances for Scotland, and one game ahead of his regular half-back partner Craig Chalmers. The two went on to star in the British Lions Tour of Australia the following summer, an experience that seemed to further refine both players, and they performed a memorable double act during the Grand Slam season in 1990.
Armstrong was the sort of player that crowds instinctively take to their hearts; tougher than teak and convinced there was no loose ball that he couldn’t claim, no matter the obstacles in his way. Armstrong made his opposite number’s life an utter misery, whether through his low, sniping runs from the pick-up, by harrying them into mistakes or by snatching the ball from their grasp before they could pass it from the base of the scrum. He was terrier-like in the loose, like an auxiliary back-row and full-back in one, as dynamic in attack as he was committed in defence. Time and again Armstrong was the one making the saving tackle or popping up in open play as a link man or finisher.
He was a British Lion only once and never played for the Test side, an anomaly that was in part due to suspicions over the speed and accuracy of his pass, and to the injuries that were perhaps inevitable for a player who never shirked a challenge.
Armstrong retired in 1999 after captaining Scotland to the final 5 Nations Championship. It was the very least he deserved.