The Olive Tree appears on the Seekers album
Say Goodbye
From the Talk of the Town (EMI Records,Columbia label SCX6278)

It was written specially for Judith Durham to sing by Tom Springfield.
(On the record album it credits Springfield - Lampert)
On the record Judith pays tribute to Tom Springfield.

Tom was Dusty Springfield's brother. He was involved in many of The Seekers hits including:
A world of our own, I'll never find another you, the Carnival is over etc
No doubt there is a web site for him and Judith somwhere.