I agree, Malcolm. This blunder has been well covered and well explained in other threads here at the Mudcat.
The 'reference' originated in a harp listserv thread from 1996. It was wrong then and it's wrong now! Lesley Nelson-Burns (aka Contemplator) and I both got sucked in by the inference in that thread that the tune melody for The Isle of Innisfree was based on a traditional tune. Not!
Let's not go around the horn again on this. I've done my best to chase down sites with my 'Alwyn' midi on them, and most have been quite cooperative in making the correction in favour of respecting and honouring Dick Farrelly's original (and brilliant) composition.
The moral of the story: Don't trust the Internet as the authoritative source on the origins of music! If I had the power I would do a webwide search and replace on the mistitled phrase!