Apple served London congregations at Bayswater and Hampstead between 1960 and 1972 before returning to Australia to take up the role of senior rabbi at the Great Synagogue, Sydney.

In Sydney he also served as a dayan and registrar for the Sydney Beth Din.

Interfaith dialogue has been a lifetime interest of Apple and one which he pursued in Sydney. He is joint president and a former chairman of the Australian Council of Christians and Jews and a life member and former chairman of the NSW Council. He founded the Christian-Jewish Luncheon Club in Sydney and has been a leader in dialogue with Islam.

Apple is an Officer of the Order of Australia for his services to the community..

Apple was an Australian Army Reserve chaplain for 15 years and from 1988-2006 senior rabbi to the Australian Defence Force.. He also served for two terms as chairman of the Religious Advisory Committee to the Services, the first Jewish representative to hold this office.

Apple is prominent in Freemasonry, being a Past Junior Grand Warden and Past Grand Chaplain of the United Grand Lodge of New South Wales and the Australian Capital Territory.

Apple has lived in Israel since 2006.

Apple has written a number of books, including :

He has also published numerous articles on Jews, Jewish history, the Jews in Australia, and various Jewish and interfaith themes. He is the author of "OzTorah", a weekly e-mail service and website presenting insights into the Torah reading, an Ask the Rabbi forum, and articles on Freemasonry, interfaith issues, British Jewish history, and the Australian Jewish community and its history. The OzTorah archives are available on his website at http://www.oztorah.com