Since 2013, he has been a member of Auckland District Health Board (ADHB).
When consultancy work dried up, he turned to teaching at Auckland Technical Institute and rose through the administrative ranks until he became chief executive officer of Unitec, one of Auckland's polytechnical institutes.
He was also the deputy leader of the Citizens & Ratepayers ticket from October 2004, serving under the leadership of David Hay.
[3][4] In October 2010 Armstrong unsuccessfully stood as a Citizens & Ratepayers candidate on the Ōrākei ward of the new Auckland Council: he was defeated by Cameron Brewer, an independent.
[8] He is also a trustee of the Sir Woolf Fisher Trust for excellence in education.