The John McCormack version from 1925 is on John McCormack in English Song, Pearl GEMM 9970, 1993. The CD was made in England, but is reasonably available in other parts of the world as well.

From the notes by Brian Fawcett-Johnston: In deciding to place When You And I Were Young, Maggie in an anthology of English song, I am well aware that it was published in America. However, the composer was an Englishman who had emigrated to America in 1856, while the lyricist and his wife, Maggie Clark (1849-66), who is the heroine of the song, were both English Canadians. There indeed was a creaking old mill on a hillside in the Ontario township where their love blossomed in 1865. George Johnson was Maggie's tutor, and also ten years her senior. They married and moved to Ohio, where Maggie died almost immediately afterwards, at the age of 16. Heartbroken, George wrote the poem the year she died, (he himself lived for a further 51 years), giving the manuscript to the Englishman James Butterfield, who published the song on 19 May 1866. It became one of the best sellers of the age. But George, who remained a bachelor, did not want the huge fortune in royalties the song brought him over so many years, he only wanted Maggie.

George Johnson's dates were 1839-1917, and James Butterfield's were 1837-1891, and as mentioned above, Maggie Clark Johnson was born in 1849 and died in 1866.

Here is a link to an earlier discussion of the song.