Posted elsewhere in 2002.
This is clearly related. Possibly comments above about the 'welsh' pronunciation of 'll' in 'belly' feed back to this version:

JOHN/HENRY
Tune: Bugeilio'r gwenith gwyn. Lyrics Unknown

There was a man, he had two sons,
And these two sons were brothers.
John Henry was the name of one,
And Henry John, the other.

Now these two sons, the found a bike.
The found it in a hollow.
And whereso'er the front wheel went,
The back would surely follow,

Now these two sons, they bought a cow.
They milked it with a spanner.
The milk came out in shilling tins,
The smaller ones; a tanner.

Now these two sons took ill and died.
They died of eating jelly.
John Henry died upon his back,
And Henry John his belly.

Notes: 'shilling' 12 old pence, one 20th of a pound sterling.
'Tanner' six old pence. One fortieth of a pound.
Jelly: gelatinised fruit cup.