The R4 programme started with the 'problem' of millions of bereaved wishing to visit the grave of their fallen one abroad. A WW1 pardre already familiar with the grave of an unknown comrade forwarded the idea of a 'national' unknown soldier via the Dean of Westminster resulting in the re-burial and service in 1920.   It was very well attended. A number from graves of the unknown were exhumed on the continent and one chosen. Even the place of his grave was not known to those making the choice. Indeed the soldier is not known nor are his beliefs.
He could have been the missing relative of any of those that passed by.