I have to admit that when I first heard the song, many years ago, I thought to myself "hey, that's pretty neat, they have put a bit of kookaburra sits in the old gum tree into the song". However, I do not believe this small amount constitutes any sort of copyright breach as it is not fundamental to the song. It it was the underlying "theme" of the chorus, it would be a different matter.
With such a long delay, I believe some sort of statute of limitations should apply, 10 years should be enough, surely a quarter of a century would be more than adequate.
I can think of so many "classical" pieces that end up with "tada"! Someone must have first thought of this and every classic composer since then has copied (don't think I am just a classical buff, it is just I do a bit of ballroom dancing and many classical pieces make great a waltz, I wouldn't know Mozart from Monkeys or Beethoven from Beetles
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