I am reading A Conan Doyle's book The White Company. In a scene set in a tavern a "gleeman" sings the following song. My question is about the song. Is this a traditional song or did Conan Doyle write it for his book?

What of the bow?
The bow was made in England:
Of true wood, of yew wood
The wood of English bows
So men who are free
Love the old yew tree
And the land where the yew tree grows.

What of the cord?
The cord was made in England:
A rough cord, a tough cord
A cord that bowmen love
So we'll drain our jacks
To the English flax
And the land where the hemp was wove.

What of the shaft?
The shaft was cut in England:
A long shaft, a strong shaft
Barbed and trim and true
So we'll drink all together
To the gray goose feather
And the land where the gray goose flew.

What of the men?
The men were bred in England:
The bowman--the yeoman—
The lads of dale and fell
Here's to you--and to you
To the hearts that are true
And the land where the true hearts dwell.