I haven't had any luck yet in trying to solve this puzzle, but I think it's worth chasing up, and worth refreshing the thread in case there's someone out there with the answer. I suspect it actually is a genuine Sussex song.

In fact in The Four Men at the beginning of the section called The Great War Between Sussex and Kent, "Golier" comes in as well:

"With this Grizzlebeard, clearing his aged throat, dutifully carolled out the following manly verse on the tune to which all Sussex songs have been set, without exception, since the beginning of time - the tune which is called "Golier. (And here he prints the tune in staff notation - but I'm not too good at working it out, and the print is poor in my edition)

"If Bonaparte
Shud zummon d'Eart
To land on Pevensey Level,
I have two sons
With our three guns
To blarst un to the de-e-vil."

I'm pretty clear none of the Four Men could be Chesterton, and they all sound very like Belloc. Chesterton was never one for long crosscountry walks if he could avoid it. Well, he wasn't built for it. Down the pub and sit writing in the public bar was more his style. Wrote some great songs too. Here's a link to his poem/song to Belloc at the start of The Napoleon of Notting Hill.

I'd love to hear Martin Wyndham-Read's Sussex Drinking Song. But the song I'd really like to hear him put a tune to would be the one later in the book:

I shall go without companions
And with nothing in my hand;
I shall pass through many places
That I cannot undertsand -
Until I come to my own country,
Which is a pleasant land.

The trees that grow in my country
Are the beech-tree and the yew;
Many stand together,
And some stand few.
In the month of May on my own country
Al the woods are new.

When I get to my own country
I shall lie down and sleep;
I shall watch in the valleys
The long flocks of sheep.
And then I shall dream, for ever and all,
A good dream and deep.