I’m getting a bit confused with the note C.
Some online sites show C as one finger left on ‘A’ while others show two fingers left on ‘A’ and ‘G’
Now I’ve just seen another note chart showing C as no fingers over any holes.
Although I don’t read music, I assume one of the above will be a sharp and another a flat…possibly. But I wonder if anyone could tell me which is which please…thanks 
C# OOOOOO (all fingers off)
C OXXOOO (what you describe as two fingers left on ‘A’ and ‘G’)
But C is often sharp like that, and works better on many whistles as OXXXOO or OXXXOX. OXOOOO (one finger left on ‘A’) would typically be very sharp, although OXOXXX works nicely on most flutes and some whistles.
Thank you so much…I’ve just tried the OXOXXX and that is a lot nicer sounding and also seems easier to play
I didn’t know about that one, OXOXXX, that will likely be easiest for going back & forth between octaves, so thanks for that tip.
I’ve found it’s easier to move from A or B to that…possibly my fingers aren’t as nimble now as younger people…but this is a lot better
It’s slightly sharper than OXXOOO, so will tend to sharpness on most whistles, but is typically both accurate and clear on flutes.
I’ve tried all those suggestions and noticed the slight differences, and this might sound strange to an experienced player but, it’s handy for me to have a few different ways of achieving notes with my fingers at times. Arthritis started in the end joints some years ago, seeing off my acoustic guitar and so this is maybe why I’m like an excitable child with the whistle…I play with my fingers nearly straight.
For someone to have explained the different C notes was good, but then to realise if my fingers are a bit stiff one day I just go with the simplest C is such a good thing. And I’ll only ever be playing to myself, unless I do a few tunes when I’m at a van meet to vanners who have had a few pints and won’t by then notice the difference between a sharp and flat unless it’s in their beer glass
One thing that nobody’s mentioned so far is that you can “half hole” the C-nat by rolling your finger off the B-hole a bit… This may actually be easier if you’re experiencing stiff fingers. With practice, this works pretty well for some folks (not for me, btw, I’m a OXX OOO kinda guy) - one of our band members does it this way all the time. At least this can give you one more option when you’re having finger problems - good luck!
Pat
Oh that’s brilliant
I’ve been practicing doing half notes and it seems quite easy for me to do. Thank you so much 
Yes, half-holing is a great alternative that I also use in some contexts but just didn’t think to include with the others… to me a useful complement to the ‘regular’ forked fingerings rather than a constant choice.
I’m grateful for all the suggestions, they have really helped. OXOXXX works well when my fingers are supple and gives a nice tone. The half note is good for if my fingers are stiffer, so both are excellent suggestions for me..
Just one additional thought on the C-nat-question. Cross-fingerings work better on whistles with a thicker tubing. Like plastic or wood (or the Dixon heavy brass model). On a whistle with thick walls the oxxooo works just fine. On whistles with thin walls I mostly use oxxxox which also makes transitioning to the next octave very easy as you only need one more hole to close. So when changing a lot between different whistles, half-holing would probably be better as it works on every whistle. But I like the whistles with a thick tube as you can easily play them almost fully chromatic with cross-fingerings like xxoxxx for a G# for example.
I’d say OXXOOO works on whistles that are designed for it, whether thick- or thin-walled. It’s a design compromise, typically resulting in a flatter C# (which you can test on a whistle normally preferring OXXXOO or OXXXOX by taping or shading the top hole for OXXOOO), which is why some players don’t like it.
Not saying that wall thickness has no influence… just that it’s not the main issue here. Indeed, a half-holed C natural can be seen as a logical exaggeration of the smaller top hole required for OXXOOO.
Im starting to find a slight roll of the whistle moves my finger to a half note then back again to B a lot quicker than actually moving my finger to half note. A bit unorthodox, but thanks to all the suggestions on this thread Ive been able to find what works best for me 
Yes the half hole is the way Im going
@ Peter, you can agree to disagree. It’s just something I learned from observation. oxxooo works on EVERY thick-walled whistle I have while it doesn’t work on some with thinner walls. Of course you could also vary the hole size of the top hole but only to a certain extent. Making holes smaller or bigger means they need to move up or down on the whistle and all the other holes will also be moved. Hole-placement on whistles is always a compromise between intionation and playability. Whistles with thicker walls can almost be played like a recorder where (approximately) leaving one hole open and then using 2 fingers to close the two holes below will make a half-tone difference. Like xxxoxx for F# – will not work 100% but for quicker tunes it will work fine. xxoxxx for G# works fine on a thick walled whistle and I don’t think you can design any thin-walled whistle so that this fingering will work (at least I never saw one on which it worked). So material is an important factor.
My last point was neither pro nor against half-holing as a technique, but to stress the interrelationship of fingerings and hole sizes as much as fingerings and wall thickness.
I don’t doubt that, but still believe it to be as much a design choice as anything else.
Oops, was too slow with my editing of my post 
. Added some thoughts above. One thing I do notice when comparing the Dixon DX204 with other whistles is that the top hole is bigger and the three top-holes are therefore closer together.
So I think when making the top hole smaller on thin-walled whistles so that the oxxooo works (in case it doesn’t) would make the top hole probably too small. At a certain size a hole won’t work properly anymore.
I did a quick modelling exercise, comparing thin and thick walled high D whistles, both optimized for tuning over two octaves, including cross-fingered C-nat and C#. The thick-walled whistle called for somewhat larger holes in some cases, but the tuning of C and C# came out almost exactly the same on the two whistles (with C somewhat sharp and C# somewhat flat). If OXXOOO isn’t working on a particular thin-walled whistle, I’d suggest the designer has made a different design compromise.
Edit: for the record, XXOXXX was sharp of G# on both thick- and thin-walled design. F# is XXXXOO, G-nat is XXXOOO, and there’s no chromatic note between the two, so I’m not sure what you’re using XXXOXX for.