What Little Ditty Is This?

Cafe Society
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If you own Queen’s Greatest Hits on CD, the song “Seven Seas of Rye” ends with some little ditty about “Wouldn’t like to be beside the seaside?” What song is this? (I was watching “Bewitched” when they began singing a little of this.) What do you know about it?

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This took me about six seconds to find on Google.

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Also, is Smoke On The Water by Deep Purpl’e based on a real event?