It didn't stop there. Aware the community deserved up-to-the-minute resources, he organised a complete refurbishment of the adjoining ambulance station.
Mr Armstrong was stalwart of the Order of St John in Whanganui for more than half a century and served both as chairman and deputy-chair of the local committee.
In 2001 he was invested as an officer of the Order of the Hospital of St John of Jerusalem - the order's highest award - by the Governor-General Dame Silvia Cartwright.
Away from St John he was active in clubs, church and lodge activities. His fundraising skills benefitted Red Cross and his service to IHC New Zealand earned him life membership of that organisation. His services were also enjoyed by the local division of the Arthritis Foundation and the Heart Foundation.
In 1995 the Wanganui Chronicle recorded the Mr Armstrong's appointment as secretary of the NZ-Ulster Trust which developed the connection between one of NZ's earliest premiers, John Ballance, to his birthplace in County Antrim in Northern Ireland. Ballance founded the Wanganui Herald newspaper.
Born in County Fermanagh, Mr Armstrong lived twice as long in NZ than in his Northern Ireland homeland.
A soldier for 30 years he served for seven years in the British Army and the rest of the time in the NZ regular force progressing through the ranks.
He spent time in Korea as a company sergeant-major in 10 Transport Co, RNZASC. Returning to NZ he was later commissioned as a lieutenant.
He became chief instructor for the School of Army Administration course that many army personnel were obliged to take if they wanted to be promoted. He retired from the army with the rank of major.
In an interview with Midweek in 2002 Mr Armstrong said the skills he gained in the army "created in my mind and working habit, a sense of order and self-discipline". Those who worked alongside him said he did everything with military precision.
Colleagues said he left nothing to chance and spent hundreds of hours to attain the goals for whatever charity he was on at the time.
Later in life he was an avid writer on Scottish and Irish history, supplying articles for the Clan Armstrong trust's quarterly magazine in Australia and Scotland and for the Armstrong clan society in the US and Canada.
In May 1988 he and his wife Margaret travelled to Scotland for the clan gathering at Liddesdale, Roxburghshire, where he handed over some of the family's historic documents left to him by the estates of a distant relative.
That community award citation said Mr Armstrong had a gift of forging links with the community and between communities: "Tom has been a tireless community volunteer, making a positive difference." He certainly did that.
Mr Armstrong was predeceased by his wife Margaret and daughter Heather.