I'm sorry to have taken 8000 years to reply to this thread, but I spoke to Barry who sang to me what he could remember of this song (which wasn't all of it). I don't have a copy of the film so I can't check what portions actually appear in it, or if the lines below will fill in all the blanks; but Barry remembers it as being only two verses long. He wrote the music, and the words are by Pete Lee Wilson, an actor/extra who played a sailor.

The scene was filmed on location in Tahiti (poor sods), and Barry says the two of them sort of improvised it just before the shoot, taping the words to a cowrie shell. Anyway, here's what he can remember, though they did lodge a copy with PRS/MCPS.

If I were a sailor I'd go to sea
I'd take my pretty girl with me
She could cook and care for me
And I'd be the pride of the King's Navy

But alas it is the law
I had to leave her on the shore
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