What I remember of the song John sang me follows. If there is more of it in his book [or any other] I would be delighted.

Chorus
Rats and snails and ringworm pies, headgehogs and birds of paradise x2

Bits of verse

....... and broke his bloody head sir
....... and now he's lying dead sir

....
....

It's a wee peewee in a peewee tree
That sings 'Pee wee pee wee ee'

Ewan McVicar