Apart from Burke, who makes high D whistles with a thumb hole for C nat?
Cheers
Two other makers that I know have offered the thumbhole are Hans Bracker and Colin Goldie. Both make very good whistles IMO.
Hans’ website: http://bracker.co/music
Goldie’s: http://www.colingoldie.de
Other makers may well do the same if you inquire with them.
I have a few Burkes that have the added thumbhole. The tuning and clarity of flatted 7th note is great on them. But I generally don’t use them like that. I cover the holes with tape. Half-holing or cross-fingering works well on the Burkes without the extra hole. YMMV.
Feadoggie
I know that Roy McManus has made whistles with Cnat thumb holes.
Actually, if you have a cheapy whistle,why not try putting your own thumb hole.
Start with a hole of about 3mm halfway below & between the A and B holes and increase to tune.
If its not great,just tape it up.
I’d think a hole between the C# (TH1) and B (TH2) holes might get a better C natural. 
Yeah, that whole terminology thing. So annoying.
Apologies,I was only trying to help.
Just to clarify,i indeed meant to place the new hole between the 1st and 2nd holes down from the fipple end.
Don’t Rec…rs often have a split hole with two small holes side by side. You can cover both easily with a finger or just one. Not recommending for whistles that you do that, but observing a fact.
Sure. That’s done on some whistles too. I assume the OP was looking for a thumb-hole for the C natural note. Double holes usually do not apply to that note on a chromatic whistle. It still gets cross-fingered or half-holed.
You mean recorders? Say recorders!
Gary Humphrey will do one like that if you like.
I make one.
Most makers can do it if you ask.
But it’s the whistle forum! You can’t say the R word in here!
Feadoggie,
That is a beautiful instrument !
Was it a custom request or an at-one-time regular item.
trill
Trill, the photo is one I snatched from the Sweetheart website. It is a standard offering I believe.
http://www.sweetheartflute.com/whistle10.html
It was the first photo I could locate with double holes. The shop foreman at Sweetheart, Joseph Mourneault, also makes whistles under his own name. He seems to be producing a couple of different hole patterns for chromatic whistles.
and there is this one too.
The use of the double holes goes go back in history. While common today on the lower two positions of the recorder with “baroque” fingering, as LI Whistler pointed out, those holes would have been larger single holes on flutes made in that era. The practice of using double holes was employed on some flutes and fifes in the 18th and 19th century, particularly in France AFAIK. So it is a potential solution/method for makers to keep in mind.
Feadoggie
Yeah, i have a Humphrey D plus (D whistle with the extra hole). He did it impeccably of course, but it turns out I don’t like it and don’t use that tube… when he made mine, the head from the D+ would also fit on a C tube, so I bought the combo. I just use it as my regular C whistle though. Should probably sell the other tube to someone who would use it.