Searching The DT for "John Henry" brings up a lot, but not the following:

JOHN HENRY / HENRY JOHN
(Trad?)

There was a man, who 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 they found a bike.
They found it in a hollow.
And wheresoe'r 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 from eating jelly.
John Henry died upon his back,
And Henry John, his belly.

Tune: Begeilio'r Gwenyth Gwyn (Mi sydd fachgen) Verse only (no chorus)
This song was learned in my youth, at wolf cub campfires (C 1960)
Shilling: 12 old pence (1/20th of one pound)
Tanner: 6 Old pence
Jelly: a gelatinised fruit cup, not the U.S. version of jam.