"Kerry Pro Low D. This name refers to instruments which are much like Overtons and are handmade by Phil Hardy. Phil sent me one and it is a lovely instrument. The differences between this whistle and the Overton Low D are extremely subtle. I’d be hard pressed to tell the difference between them. Although disputes have existed about the Overton name, if one puts these aside and stays on the level of evaluating the whistle itself, what you have is two virtually identical and OUTSTANDING instruments. "
In my experience (I have a low E Overton and had borrowed low D Kerry), the Overton played much more to my taste. It seemed to me much more “balls”, so to say. And more soul. The “cosmic drainpipe” sound wasn’t in Kerry’s sound.
I have got two KP low D both old version (KP low F,G and rare soprano D). The first one is very easy to blow the second one is very difficult to overblow. I had Overton low D too. I sold it because my first KP sounds wormer in first octave. Overton in my opinion is easier to play.
The regular Kerry Low D is very easy to tell apart from the Kerry Pro, since the Kerry will have a plastic head, either black or blue for the fipple end, whereas, the Kerry Pro is all aluminum, and has flattened sides at the fipple like the Overtons. Hobgoblin is still selling these, and they are supposed to have a pinned block, visble from the flattened side, which seems to be a quick and easy way to tell newer ones apart from Overtons. Here’s a link to some pictures posted last September of a new one where you can see this:
However, I did come across this post, that says that a Kerry Songbird was also marked Kerry Pro on the underside, but I haven’t heard whether this was a standard marking for the Songbirds or just a fluke. Here’s the post: