He was a versatile, tough-tackling and energetic midfielder who played mainly for Chelsea, joining the club from Bradford Rovers in 1946 for a fee of 100 guineas.

Armstrong had a testimonial staged by Chelsea for their long-serving player and a crowd of 14,000 at Stamford Bridge were on hand to see newly-promoted Leicester City beaten 2-1 in May 1957.

[1] After leaving Chelsea in 1957, Armstrong emigrated to Gisborne, New Zealand and continued to play football there for the Eastern Union club.

In early 1958, while in Gisborne, Armstrong was offered a playing contract at Melbourne Hakoah in Australia, which he declined to continue on as the New Zealand Director of Coaching.

[2] Later in 1958, while still playing for Eastern Union, Armstrong was selected in the Auckland regional representative side to play touring Israeli club Maccabi Haifa[3] Armstrong then moved to Auckland, signing for North Shore United and later Eastern Suburbs, winning four Chatham Cups.