Did any DF23 in France come from southwest Britain?

[alan trowel hands.]

As to the thread question, I dI think some people have seen L23 as the oldest so far identified L21 downstream SNP.  What is variance telling us?

Yes, although we now know that DF49 is upstream of DF23 (I think you mean DF23 not L23).

The interclade ages between DF23 (or just use the M222 data) and other major groups like DF23, L513 or the Scotls modal folks is quite high.  DF49/DF23 must have been an early branch off L21, or I guess we should say off DF13.  It's not really that DF23 is old, just that its branch off of DF13 is old.  
It is worth noting that that some of the DF23* branches, like the Wales SW England branch, have old interclade ages with M222 so DF23 does in fact have an "old" coalescence age whereas M222 does not.

How old?

[Mikewww]

The 49-23-21-HyM variety has an STR signature that includes 413a<=21 511=11
557=17 565=11 (456=15 481=24). Those that have tested so far, have come back as
DF23*. I encourage testing for DF23 for anyone in this variety.

I frequently analyze long haplotypes in the Irish, Scottish and British FTDNA
projects looking for matches. Occasionally I'll look at other geographies and
found an interesting prospect for DF23 testing. He fits this variety pattern and
here are his closest GDs in it. Nothing really close, but perhaps there is
ancient connection between Bodamer and the rest?

fB1536 Bodamer - Germany, Baden-Württenberg, Grünwettersbach 49-23-21-HyM TXC93

f132540 Traynor - Ireland, Ulster, Co. Cavan 49-23-21-HyM F8S6Y
fN5677 Traynor - Ireland, Ulster, Co. Tyrone, Dromore, Corlaghdergan 49-23-21-HyM
5FS7D
fN33146 O'Kelly - Ireland 49-23-21-HyM
f108030 Trainor - Ireland 49-23-21-HyM
f159039 Trainor - Ireland 49-23-21-HyM GFCKV
f27822 Shannon - Ireland 49-23-21-HyM P5A89
f100219 Kelly(Ui Maine) - Ireland, Connacht, Co. Galway, Raheen, Gort 49-23-21-HyM
W2QBJ
f79367 Kelly(Ui Maine) - Ireland 49-23-21-HyM VGMYE
f160027 Madden - Ireland, Munster, Co. Clare (?Limerick) 49-23-21-HyM TEB6B
f84928 O'Kelly(Ui Maine) - Ireland 49-23-21-HyM Y848K
f162015 Kelly(Ui Maine) - Ireland, Connacht, Co. Roscommon 49-23-21-HyM
f185074 Pugh - zzzUnkOrigin 49-23-21-HyM
f107869 Kelly(Ui Maine) - Ireland, Leinster, Co. Laois 49-23-21-HyM V87H6
f189772 Pugh - Wales, North, Gwyneed 49-23-21-HyM
f128257 Pugh - Wales 49-23-21-HyM
f60472 Pugh - Wales 49-23-21-HyM 7Q7CY
f108037 Pugh - Wales 49-23-21-HyM F4SD9
f14875 Thomas - Wales, South Carmarthenshire, Llandybie 49-23-21-HyM XU9XN
f167278 Armstrong - Ireland, Ulster, Co. Tyrone 49-23-21-HyM RPEAK

Armstrong is pretty iffy as far as being included in this group or not.

[Roger Buttermore]

So even though I have had FTDNA Deep Clade, the DF23 @ $29.00 would be helpful OR should I wait on my Geno 2.0 results first?

[Jdean]

So even though I have had FTDNA Deep Clade, the DF23 @ $29.00 would be helpful OR should I wait on my Geno 2.0 results first?

DF23 is in Geno2 so wait it out