I'd suggest contacting Norm Christie, a Canadian military historian. He worked for some years for the Commonwealth War Graves Commission in France, and was responsible for identifying several previously unknown soldiers. He was the one who identified the grave of Kipling's son.
There is some chance that Mannock is buried in one of the thousands of "Known unto God" graves. If the burial or reburial party found any insignia it might identify him as R.A.F., but equally likely there were no identifying items.
Christie's books are available through Chapters
www.chapters.com which operates much the same as Amazon does in the U.S.