Dermot Ryan was Director of Lidcombe Credit Union Co-op 1952- 1960; Foundation Chairman City Council Employees Credit Union, 1963-1970; Director NSW Credit Union League in the 1960s; National Director CUNA 1967-69. With Ken Miller, he laid the foundation of the Stabilisation Fund which became the Reserve, and of the Central Banking System.
He encouraged CUNA Mutual to set up in Australia. He was instrumental in implementing ideas such as Savings Protection Fund. He served in a number of capacities for AFCUL and was Hon. Sec. Treasurer for the Australian Credit Union Historical Co-Operative in the 1980s.
Dermot Ryan provided an oral history interview for the credit union movement in 1989 when he was interviewed by Daniel Connell.