It was indeed; the book was edited by Frank Purslow and published by the English Folk Dance and Song Society in 1965.  It contained songs from the Hammond and Gardiner collection, and was named for one of those songs.  That doesn't help with the question that Moobear actually asked, though.  Bob Bolton has already said as much as can usefully be said about that aspect of the song; the marrowbones probably don't really have any significance except as a joke.  They occur (the eggs are optional) in most versions, though not in the song's descendant Johnny Sands.

The song is widespread, and turns up in all the usual countries.  The consensus seems to be that it was originally English, but it has acquired Irish tunes in many cases, and has been localised to all sorts of places.  G. Malcolm Laws assigned it his classification Laws Q2, and here it has DT number #344.

Examples in the DT:

MARROW BONES  With tune; source unspecified.
OLD WOMAN FROM WEXFORD   with tune; no source named.
TIPPING IT UP TO NANCY   Irish version with tune; no source named.
THE RICH OLD LADY   American version, with tune, noted by Alan Lomax from James Baker of Iron Head, Sugarland TX, in 1934.
EGGS AND MARROWBONES 4   American version from "Uncle Tom Barker" of Oklahoma.  No tune.
THE AULD MAN AND THE CHURNSTAFF   With tune; from Sam Henry's Songs of the People, collected by A.E. Boyd from John Parker of Mayoghill, Garvagh, c.1927.  A Scottish version migrant in Ireland.

In the Forum:

The Old Woman from Wexford   Discussion, with an unattributed set of words including suggested guitar chords.  No tune.

Old Woman from Belfast   Discussion largely about a completely different song, but including the text of Tutheree Oo, and Tan from the Universal Songster (1828).

Johnny Sands   Appalachian set, no source named or tune given.

Entries at the  Traditional Ballad Index:

Marrowbones
Johnny Sands [Laws Q3]

At the  Max Hunter Folk Song Collection:

Johnny Sands  As sung by Mrs. Olive Coberley in Weaubleau, Missouri on October 7, 1958.

There are a number of broadside copies of Johnny Sands at  Bodleian Library Broadside Ballads.  The texts vary very little.  Here is one:

Johnny Sands  Printer and date unknown; presumably mid 19th century.

Malcolm