Jack Bannister joined the Air Force in 1939 and flew Mosquitoes on Photographic Reconnaissance during the war. He returned to Treasury at City Council, then to Audit, then to Cleansing Department. In 1963, when Dermot Ryan proposed a City Council (Sydney) Credit Union, Jack Bannister became a Founding Director, then Chairman from 1970 to 1985 and Director to 1997. He was a member of the AFCUL Annual Meeting Organising Committee, the 1979 World Council Committee and in 1987 became a Vice President of the Institute of Credit Union Directors.
In 1985 he became a Foundation Member of the ACU Historical Co-operative in which he was a Deputy Director and volunteer worker until 1996. He became Director of the Historical Co-operative in 1991 representing NSW members until he retired due to ill health in 1996. Helped Tom Kelly to set up and organise the co-operative's AGMs and Reunions in Queanbeyan.
Jack Bannister provided an oral history interview for the credit union movement in 1989 when he was interviewed by Richard Raxworthy.