Chris, I've nothing to contribute on the early history of the song beyond what has been mentioned (Watersons notes and thread 47543), but my notes include a parody called 'Country Boy'. Haven't checked, but it may have come from the DT or the Forum. As it's short, I'll re-post it here:

[1997:] Parody 'Country Boy' (by Cat Fox?, Holly Tannen?)

I hates to rise when the sun she rises early in the morning
I hates to hear them small birds singing merrily upon the lyelam
And a pox on the life of a country boy
Who's allergic to the new-mown hay

I hate larks and I hate thrushes early in the morning
I hate birds of every size merrily upon the lyelam
And when they start their bloody song
I want to poke them in their little eyes

In winter when the sky is grey early in the morning
We sit and watch TV all day merrily upon the lyelam
But in summer when the sky is gay
We sit and watch TV all day