Haven't found any of Sampson's XXI Gyspsy Folk Tales online - there's a later imprint here though which is worth checking out:

Gypsy Folk Tales

A very fine collection. Happy hunting!

*

I first read the story around 1984 and I remember telling it a lot it that summer whilst on the hoof. Not sure when the Squirrel and the Fox were replaced by the two hares, nor yet when these hares became Lamachree & Megrum, but that's the way of things. I still tell it now as Lamachree and Megrum as I have been doing now for 15 years at least. My favourite story? Very likely. It involves an episode of blindness when Jack is forced to pull out his eyes in payment for meagre foodstuffs. A cracking tale as they say!