I have just seen a reference to the first review of this book that I am aware of and it is printed in, of all places, The Economist! It is a factual account and a precis of the contents rather than any statement about the value of the book or a comparison with anything that has been published in the past.
I thought the first paragraph of the review was arresting -

ENGLAND, the Germans used to jeer, was "the land without music". They were wrong, as Steve Roud robustly demonstrates in "Folk Song in England". Surveying English musical life from the time of Henry VIII—a keen musician and composer—to the mid-20th century, when folk song lost its roots, he shows what an intensely musical land England has been.

You can read the review on-line at by clicking here.