There's an excellent article in the 15 June 2018 edition of the Times Literary Supplement
by Jem Poster that examines Jefferies' influence on Edward Thomas'. Here's the beginning:
Excavating the future
Richard Jefferies and Edward Thomas: a spiritual affinity in poetry and prose
When Edward Thomas wrote his biography of Richard Jefferies (published in 1909) he was paying homage to a writer who had influenced him, at the deepest level, from childhood onwards. We should beware of over-simplifying the complexities of literary influence – shared concerns do not necessarily imply the direct passage of ideas from an older to a younger writer. But it’s clear that Jefferies’s works played a crucial role in Thomas’s intellectual and imaginative development, and that Thomas’s admiration for his predecessor constituted a form of filial devotion. When he discussed his early reading in the memoir posthumously published as The Childhood of Edward Thomas, he accorded Jefferies an importance allowed to no other writer mentioned in that context.