[3] Tyrrell succeeded Rear Admiral Sir Leighton Bracegirdle as Official Secretary to the Governor-General, William McKell, in March 1947.

[5] Tyrrell had a small but pivotal role to play in the establishment of the Australian Conservation Foundation.

The ACF began in the second half of 1964, after a suggestion was made to Tyrrell by The Duke of Edinburgh while visiting Australia in 1963.

He voiced an idea that Australia could become involved in conservation by establishing a branch of the World Wildlife Fund.

[6] Tyrrell was appointed a Knight Commander of the Royal Victorian Order in 1968, during Lord Casey's term.