Gillan’s Apples as published on sessionorg here looks to me to be in A mixolydian, with some raised bottom Gs at the ends.
Spot on. Nothing to do with Lydian.
There seems to be a lot of confusion over names for Gillan’s Apples. It’s a jig in G (I’d argue with that of course 
) which I think has also been called Apples in Winter (more confusion). I learned it off the Totally Traditional Tin Whistles album.
… and there I go, not knowing the tune (Gillan’s Apples) expecting to look at it and be able to say with confidence that it couldn;t possibly be in Lydian mode … and I can’t … I think it’s at least ambiguous. Strange ending to each part right enough. Is it enough to make it Lydian? Or are those just passing notes in an otherwise straight major tune? And the answer is … I don’t know. Didn’t think that would happen …
Well the B part is Lydian the way I play it. No C nats and no D sharps. I agree that the A part is G major unadorned. Shoot!
@Steve re: Cronin’s Hornpipe
Even if you leave out the Cnat in part B, and play a D instead of D# (the D# is just a dramatic device, to lead to the E), you still have the tune returning to a straight G major, repeating itself as in part A. And, as I said, part B bar 1 is a variation in D major (C# leading to D), bar 2 in E minor. No evidence or need for G Lydian anywhere.
@Ben
Do you refer to Gillan’s Apples as seen on sessionorg? That tune is firmly rooted in A, not G Lydian, either A mix with some sharp bottom sevenths, or A with some flat top seventh. I tend to think A mix, with added drama at the bottom.
I agree with you on Cronin’s, but not on Gillan’s Apples, about which I still can’t make my mind up. Firstly, I would say that the tune as transcribed on thesession.org is firmly in D, not A, but I was making allowances for the fact that Steve obviously plays it a fifth lower (or a fourth higher, however you want to think about it - basically with one less sharp in the key signature), so, when he suggested that it was in G lydian, I was - sort of - agreeing with him by not mentioning the key signature itself and mentally adding in “D” when I said that I wasn’t sure whether it was lydian or not. All that being the case, whether it’s straight major with an inflection, or lydian, there is no doubt in my mind that the tonal centre is D, not A, as it is transcribed on thesession.org.
Gosh, this stuff get’s tricky when you start having different perceptions on the same thing, doesn’t it?
Well this is it with a lot of Irish tunes. If you dissect them you find that, say, a four-bar section could be considered to be one mode and the next four bar section could be in a different mode. Certainly some tunes have A and B parts you could consider to be in different modes. With my version of Cronin’s, in the B part I play one C sharp in the first phrase which does not appear again in the rest of the tune. The same section of tune contains only the notes of the G Lydian scale (in my version) - so no C nats and no D sharp. I think the single C sharp is enough to give that section a Lydian feel whether you regard the B part or the whole tune Lydian or not.
@Ben
Do you refer to > Gillan’s Apples > as seen on sessionorg? That tune is firmly rooted in A, not G Lydian, either A mix with some sharp bottom sevenths, or A with some flat top seventh. I tend to think A mix, with added drama at the bottom.
I think we’re still confused as to the identity of this tune. 
I just remembered. “My” Gillan’s Apples is the second tune of track 1 on Chieftains 2, if that helps to identify it. It appears to have G as tonic, so I don’t know what all this A and D talk is about. Whatever else it is it is in a major-sounding mode and is not Mixolydian. Unfortunately I can’t listen to it as my vinyl facilities are temporarily dead. Perhaps someone could confirm or deny the tonality and the presence or absence of that C sharp at the end of each part…
Here be it on the notoriously-wonderful The Session tune base. Click on sheet music and observe the wonderful C sharps…
Ah, that one. Yes, different tune. And it isn’t in Lydian at all. It’s in plain old G major, with a (very common) modulation to D major for the cadences. It’s not even a modal tune, properly speaking.
Now Ben, it can’t be plain old G major (and certainly not because The Session says so! 
) if every C in it has become a C sharp. OK, both Cs, but they are at pivotal points in the tune, the end of each part, and they add a very distinctive flavour. A sort of, er, Lydian flavour, I’d say, which nothing else in the tune serves to counter. Are you setting the bar too high?
Ah, that Gillan’s Apples is like the version in Geraldine Cotter’s tutor, there called Gillian’s Apples, which goes like this:
T: Gillan's Apples
M: 6/8
R: jig
K: G
g3 B2A | GAG GBd | efe edB | dBA ABd |
gfg B2A | GBd g2 a | bag fag |1 fdd d2f :|2 fdd d2e||
faa faa | faa agf | gbb gbb | gbb bag |
faa faa | faa aga | bag fag | fdd d3:|
Here for comparison thesessionorg’s version of it, as pointed out by Steve:
http://www.thesession.org/tunes/display/1855
(Ben, I referred previously to tune 1854, not 1855)
T: Gillan's Apples
M: 6/8
R: jig
K: Gmaj
g3 B2A | GAG GBd | efe edB | dBA A2 D |
GBA G2D | GBd g2 a | bag fge | ed^c d2:|
faa faa | faa agf | gbb gbb | gbb bag |
faa faa | faa aga | bag fge | ed^c d2:|
Just a few small changes, and no C# at the part endings.
Those C#s in thesessionorg’s version are IMO not pivotal at all, but are just a temporary change to D major in the bar, same function as in Cronin’s, what I called a “dramatic devise”, a temporary (1 bar) key shift.
I think to hear some real “Lydian flavour”, try on a D whistle a common tune in G major, which uses all seven notes (not a gapped scale), and firmly rests on G, but play all C naturals as C sharps.
Well I hear something nice and something different at the end of that tune. I find it odd that you can just say that it’s a temporary change to D major for one note (quite a modulation) - it wouldn’t be a modulation at all had the note been a C nat - and say that it isn’t pivotal. The tune sounds lame to me without those C sharps. They lend an air of unresolved expectancy for what is to come and a mighty cadence if it’s the last tune in the set. Very Lydian! And that version isn’t just the Sessiondotorg’s. It’s Willie Clancy’s, the Chieftains, and mine! My last word, chaps. At least we’re not shooting at each other… 
It’s a bit odd listening to people arguing about the mode of a tune when it turns out they aren’t talking about the same tune and when they do agree which tune it is, 2 out of 3 of them admit to not playing it.
I’m hardly the first person to point this out but trying to understand Irish dance music in terms of modes will only get you so far. Many tunes are far too complex for a mode to tell the whole story. There are other significant factors - tonal centres (many tunes have more than one “tonic”), gaps in the scale, for example.
BTW the Gillan’s apples in G on thesession.org was submitted by me and I must have put it in G major but you could make a good case for the tonic, or most important tonal centre, being D. In which case whether the exact combination of notes used in the tune corresponds to the old lydian church mode strikes me as of no interest whatever. (Same for Rakish Paddy which surely has nothing to do with any variety of C mode or key.)
Individual interpretation plays a big part too. One of the nicest versions of Cronin’s hornpipe I have heard is that of Tommy Peoples on one of his 1970s recordings. There are no C naturals in it at all, which gives it a lovely feeling - far removed from G major (just replace all the Cnats with Ds and you’ll get the idea). There’s possibly one C# in the 2nd part, would have to listen again and check, but to jump on that C# and say: Aha! Lydian! seems to me rather comical in a Monty Python sort of way.
But… carry on lads.
I can’t see any problem at all in saying that Gillan’s Apples (now that we’re talking about the same tune) is firmly in G major, not lydian. It behaves in much the same way many classical (using the word in its narrow sense) pieces do - it modulates to D, briefly, for the cadence. That’s what give the air of expectancy - one’s ear is expecting it to return to its proper key, which is G major.
Just to clarify: both Steve and me play Gillian’s Apples as on Chieftains 2. I did not know the version as #1854 on sessionorg. Not sure if Bill knew it, but it is an easy tune to pick up.
One difficulty of finding a common reference which tune we are talking about. Steve mentioning Chieftain’s second album made that clear. BTW there it is called “Gillian’s Apples”.
As to the rest of your post StevieJ: much appreciated, thank you!
Just a general comment.
G major is not a MODE. It is a key signature.
It can be a default descriptor for the G Ionian Mode because their degree values coincide.
The key signature of G major (refered to as G key signature) comprehends the following modes
which are most relevant to British and Irish music
G Ionian
A Dorian
D Mixolydian
E Aeolian
However, having said that, if someone means to convey their reckoning of the tonal centre of a piece based on thier preference of a chord triad , then G would refer to the resolving harmonic triad for that piece and that person is (potentially confusingly IMO) referreing to the piece on that basis.
That triad can be applied to
G Ionian (key signature of G)
G Lydian (key signature of D)
G Mixolydian (key signature of C)
As you can see that alone will not tell you the mode because there are three possibilities for the mode.
TBC
“G major is not a mode”. Er … that’s what I said. But it’s not just a key signature either. It’s a key. I.E. not a mode in the same sense that we use modes when we describe Irish music. And modal music in the Ionian mode is not, strictly speaking, the same thing as music written in the major key. There is a disctinction, hard to describe but easy to hear, between modal music in Ionian mode and music written in the standard, major key as used in the classical sense.
If we see that the notes in the piece are
D E F# G A B C# with nothing else
then the piece is clearly in the key signature D (major),
not G (major). If you notated that as key sig. G you would have to make all the C# accidentals which is very untidy and defeats the conventions for assigning key signatures.
Now, if you have a situation where all the notes are in D key sig. but the person describes the key as G major on the basis of a reckoning of the tonal centre based on a preferred resolving chord (G B D), then you have a situation where that person hears the tonal centre as G in key signature of D (notes D E F# G A B C#). That is G Lydian.
Sometimes whether a tune is G Major or G Lydian varies from player to player.
An example is Sean Reid’s Reel, which I have heard played by some people with C sharps throughout, by some with C naturals throughout, and by some with the C’s alternating. It is very common if not universal among uilleann pipers to have their C’s vary, in some cases due to the phrase involved, in some cases seemingly willy-nilly. So if one it talking about the tune Sean Reid’s Reel as it’s actually played (and not some theoretical construct) one could not make a definitive statement as to whether it’s G Major or G Lydian.
What’s very interesting, and strange, is to hear old-time players who play C#s throughout every tune, even tunes (or phrases in tunes) I think of as being in C Major. So, I heard two old Irish guys playing flute playing things like Gravel Walk and Rakish Paddy with C#s throughout. What mode would THAT be?? (The tonic starting on the sharp 7th of a Major scale.)