I’m fairly new to the flute and have been playing a one-keyed baroque flute (i.e. it’s in D with an Eb key). Recently though I acquired a 19C eight-keyed flute and am learning to play it. However I find it difficult to manage the Bb key with my left thumb. Up to now I’ve been positioning the thumb so that I can roll it on to the key, but I that is setting up tension and I can’t always play it cleanly, without blips. I’ve tried balancing the flute just on the first (or is it the third) knuckle of the first finger, so that the thumb is not touching the flute at all, but it feels a bit precarious. Also I’m not used to the extra weight of this flute - the keys make it quite a lot heavier than my baroque one. I’ve started looking for YouTube videos but so far haven’t found one that deals with the left thumb, and it’s now past my bedtime!
I’m very interested in this question too! Others will likely comment on different holds – but on the question of the left thumb, what I do is the same as Steffen Gabriel in this video: I let it rest next to the Bb key and only lift it/move it whenever I need to use the key.
It is normal for that hold to feel precarious at first. Getting to know just the right balance is a process. For the first few months of learning, I continuously read and re-read the segment from Grey Larsens tutor about setting the correct technique for holding the flute. Terry McGee’s archived article about ‘Rockstro’ hold is also very informative.
When I think about the shape of my left index(playing a rh flute), the arc is not formed by muscling finger back to form a perch. The shape of the left index can’t be formed at all without the flute body there to fit it. Instead think about placing the middle of your index finger on side of the flute but to the left of the first tone hole, then allowing a curve to form in the finger by moving your hand inwards below the flute and to the right across your body. The whole time the left thumb is free to move
As you continue to get to know a hold that works for your body and your flute together, you may slowly identify tension that is actually not needed or contributing to keeping the flute secure. Some muscle engagement is reactionary to the concern of dropping the flute. That tension will release with time, and deliberate attention to keeping only the muscle engagement that contributes to keeping the flute secure
Google the three point “Rockstro Hold”. Jem has a good video explaining it.
It is beneficial to use the correct, balanced, ergonomic hold from the start, even if you don’t have or use Bb key. The Rockstro Hold allows your fingers much more freedom of action.
Many thanks to you all - that is a lot of help. I’ve been experimenting with the Rockstro hold and now it all feels a lot more possible. 
Just a +1 for Jem’s video on the 3-point hold. I was forced to look for a better hold when I got a Boosey flute with touches for C and Bb for the left thumb and hence nowhere practical to put the thumb for supporting the flute. It took a little time to become comfortable but I believe this hold gives more freedom to the fingers and I never have to adjust the support while playing.
After a couple of weeks I’m much more comfortable and secure with this, to the point that it feels perfectly normal. In fact I sometimes find myself using it with my baroque flutes.
Presume you’ve also noticed Steffen’s RH pinky is anchored on the Eb block. That gives a stability when the LH thumb isn’t providing a countering force.
When things go wrong and will not come right,
Though you do the best you can,
When life looks black as the hour of night –
A Rockstro grip is your only man.
There is also a keyed alternative to the thumb Bb key… which is a long Bb key adjacent to the C-nat key, sometimes called index Bb which is operated no by the thumb but by the RH index finger. I have this on my Lejeune flute. Feels much more natural to play.
I’ve said this before, but I still don’t see the point of the Rockstro hold. I’m glad it works for some people, but I don’t understand what its inherent benefits are.
People say it enables you to use the Bb key, but I’ve never had the slightest difficulty using the Bb key, and I don’t use the Rockstro grip. When I’m using the Bb key, my right pinkie provides the forward-facing pressure needed to hold the flute stable. When I have to use the Eb key, my left thumb does it instead. I never have to press both keys at the exact same time, so there’s never any instability.
Moreover, I’ve watched tons of professional silver flautists play, and none of them seem to use the Rockstro grip despite having to use both an Eb key and a left-hand thumb key constantly. This further convinces me that it’s unnecessary.
I prefer Grey Larsen’s hold. Maybe I’ll change my mind someday, but I doubt it.
Anyway, I’m glad people are doing what works for them!
It’s interesting when this topic comes up to see the range of holds used by Irish flutists.
Part of it is which “anchor fingers” you use.
Here as we know Matt Molloy keeps his lowerhand little finger down fulltime, even when playing E. Then jump to 9:34 to see a completely different way of holding the flute.
Matt Molloy - live on The Session
Personally my hold has always been the same as Boehm flutists not because I started on that instrument but because it came naturally. (I started on Irish flute, self-taught.)
Since you always have your upperhand index finger on the flute when depressing the Bb key there’s no instability.
BTW the longstanding English word is “flutist”. “Flautist” is an artificial word coined by a poet for a single poem, based on Italian “flauto” (flute) and for some reason has been picked up and perpetuated by people outwith the fluteplaying world, while generally avoided by those within it.
(The magazine of the US fluteplaying world is titled The Flutist Quarterly)
It’s like the word “bagpipist” which unfortunately I’ve been listed under, on programmes, on several occasions over the years. No piper would use such a silly non-word.
This is fascinating! I was always told that classical flute-players - particularly those of an older generation - insisted on the term “flautists” and corrected anyone who said “flutists.”
I never particularly liked the term “flautists,” so if classical flute-players generally avoid that term, so will I!
Though I don’t hear the alternative, “flutists,” used very often in the Irish trad community. It’s more common to hear “flute-players.”
This is something I struggled with in the beginning. After trying different ones, I landed on something very similar to the Grey Larsen/classical hold. The main difference is that I depress the Eb key for notes that don’t involve my bottom hand. I never had any issue with stability or using the Bb key and, fortunately for me, at least with my flute, venting the Eb key does not make any perceptible difference.
@Cyberknight I was coming from the baroque flute, and was used to taking all the weight with the left hand - the right hand did nothing to support it and there was no need to provide forward-facing pressure.
Boehm flutes are very different, with two adjacent thumb keys with a roller between them so that the player never needs to lift the thumb. No need for a Rockstro-type hold!
@pancelticpiper Forgive me for pointing out that while “flutist” may be normal on the US side of the pond, here in the UK and also the former Commonwealth the name is “flautist”, and unlikely to change anytime soon!
I know recourse to the dictionary has been said to sound the death knell of an internet discussion but the OED has flutist from 1603 and flautist (from the Italian) only from 1860. So at the time there were probably no baroque flautists.
I like the three point hold. I do tend to rest my top-hand thumb and bottom hand little finger on the flute but it’s just somewhere to put them when they don’t need to be loose. I often take the opportunity to stretch my bottom hand fingers when playing top hand notes.
Seems to me that using the lower-hand little finger, while depressing the Eb key, as your “anchor finger” comes from “classical” flauting (the Boehm and Baroque flauts) and I believe is what’s shown on the 19th century fingering charts for the original orchestral wooden 8-key flauts.
Of course people starting on keyless flauts, or whistle, or uilleann pipes couldn’t have that built into their playing, and it certainly is foreign to me.
When I started playing Irish flaut in late 1970s I used the fingerings that I observed from the players I could see, there being no internet. These flautists and whistlers used their lower-hand ring finger as their “anchor finger”. I dawned on me later that that was just one expression of a perhaps unconscious system of anchor fingers. These add more “points” to however many “points” are part of a theoretical flaut grip.
Back to the “flaut” thing, Nancy Toff (who is a good person to know about) wrote in The Flute Book:
“On an average of once a week someone asks me “are you a flutist or a flautist?”
My answer is always a vehemently declaimed “flutist!”
Less decisive people may call me a “fluteplayer” or even a “fluter”.
But please don’t call me a flautist.
Since the English term “flute” is obviously related to the French word “flute” it follows that a player of the instrument is a “flutist”, first appearing in print in 1603.
“Flautist” didn’t appear until Nathaniel Hawthorne used it in The Marble Faun. Significantly Hawthorne was living in Italy.”
Toff then mentions that multiple guides to English usage (A Dictionary of Modern Usage, 1926, Dictionary of Contemporary American Usage, 1957, American Usage and Style, 1970) urge the usage of “flutist”.
“Toff then mentions that multiple guides to English usage (A Dictionary of Modern Usage, 1926, Dictionary of Contemporary American Usage, 1957, American Usage and Style, 1970) urge the usage of “flutist”.”
Sure, but that is American English, while British English uses “flautist”. The history of the words is mildly interesting but not particularly relevant.
Anyway, I apologise for any offence, which wasn’t intended. I think it was Shaw who described us as “Two countries divided by a common language.” 
There it is! Two people separated by a common language. No offence whatsoever.
It’s my decades of studying the history of English that makes “flautist” jump out as what would be called “Latinate” or “inkhorn” English writing, the style so popular centuries ago in which English poets would grab Latin (or Greek or Romance) words and pepper their poems with them. Poets created new “inkhorn” terms by the hundreds, but very few got any traction.
I don’t think either flutist or flautist are used much in English English. In the situations where people talk about pipers, whistlers and fiddlers they talk about flute players and melodeon players. To me the ‘ist’ ending for any instrument player suggest it’s their job, and usually not as a traditional musician and probably as a soloist - though the Wikipedia page for James Galway describes him as a flute player. It may have gone out of fashion along with the RP English accent. Hard to imagine ‘flutist’ in RP.
(yes, I know James Galway doesn’t speak English English - he didn’t write the page)
“Flautist” is ‘always’ used in English English in the classical music world here, though I suppose that may gradually change. I am mainly a violinist, in an amateur classical orchestra, but I do sometimes play the fiddle in a ceilidh band!