I recently aquired this high D/C wood whistle set with a flute head too. I love how it plays and sounds. (The whistle. I can’t manage a sound out of the flute head. :))
It seems to be quite similar to O’Riordan whistles i’ve seen online but the only mark on them is the carved in the wood shamrocks. No names or serial #s.
As I had only the lower half of the whistle, I sold it in 2004-2005 to someone with an upper half, who could actually make use of it. Sorry, but I cannot add anything beyond what is in the 2004 thread.
Best regards