First heard the song sung by one Warwick Brock, back in the 60s. Alas Brockie is dead just now. Howsomever, he explained the phrase "to hear the nightingale sing" was a euphimism for sexual co-habitation. Run through the words above and you'll see it makes sense. Anyone else caught up with that theory? Just don't fiddle in your knapsack!

Cheers - Sam