In three stints in the WANFL (later WAFL) Armstrong coached 265 league games. After coaching Mount Barker with some success in the late 1960s, he returned to Perth where he was a fitness trainer for the WANFL umpires in 1969 and 1970. Rejoining Perth Football Club the following year, he led the Perth reserves team to three successive grand finals, winning premierships in 1971 and 1973.[1][2]
After being appointed league coach in 1974 he made an immediate impact, making the grand final in 1974. This was followed up by winning the 1976 and 1977 WANFL grand finals. After losing the 1978 grand final, and seeing Perth fall to the lower reaches of the WANFL ladder where they have remained to this day, Armstrong briefly became director of football at Perth, but one game into the 1980 season when Peter Burton resigned[5] left to join WAFL chopping block Subiaco.[6]
Armstrong coached three season with the Lions, but won only twelve of sixty-two games: indeed in his last season amidst popular cries of "pity poor Subi",[7] the Lions were on target for a winless season before beating East Fremantle in their seventeenth match. Armstrong, who had never been reported either as a player or coach, was also reported in his third last match for misconduct towards field umpire John Morris after he criticised a decision, but was exonerated.[8] After this disastrous season which had seen calls for a mid-season sacking, Armstrong was not offered another contract by the Lions[9] and left to work as a commentator for the Australian Broadcasting Corporation (ABC).[1][2][10]
Almost a decade after leaving coaching, Armstrong returned to Perth to coach during the 1991 season. He retired from coaching after the 1993 season.[1][2][10]
^ abcd"Legend laid to rest". West Australian Football Commission. 10 November 2009. Archived from the original on 24 March 2012. Retrieved 10 July 2012.