Philippe, it seems to me that what you describe as a
"single reel" is what we call a reel "played single" -
i.e., without repeating the parts. This almost always
refers to reels where each part consists of a four-bar
phrase repeated (with minor variations); repeating
the whole part gets really boring, but is often done.
Writing about the introduction of quadrilles into
Ireland and the adaptation of the native music to
suit the new dances, Breathnach writes:
"A tremendous body of music in 4/4 and 2/4 time
developed for these dances. These tunes, of which
those in 4/4 time are known in Clare as single reels,
have a boldly accented rhythm with a pleasant
melodic jingle and on that account would serve
admirably as an introduction to the music for the
As I said in a previous post, he seems to contradict
himself in CRE II, where there is a section called
"Polkas, Single Reels, Etc." with all but one of the
tunes in 2/4; and on a cursory inspection, the only tune
explicitly stated to be a single reel is "All the Ways to
Galway", in the "Reels" section. However, under "Polkas,
Single Reels, Etc." he has two tunes which are listed as
"single reels" on Jackie Daly's first album: "Biddy Martin"
and "Jer the Rigger" - both in 2/4, but with a slightly
different feel to the regular Sliabh Luachra polkas.
All this implies that there is more to the definition of a
single reel than just the number of bars. For example,
"The Mermaid of Mullaghmore" (a.k.a. "John Doherty's
Reel"), no. 134 in CRE II, is played "single", but is quite
different in phrasing and style to the tunes mentioned
above - I think, anyway.
Many of the reels played in Sliabh Luachra are fairly
simple tunes, played single; an example, again from CRE
II, is no. 192, "The Lisheen Reel". Such tunes seem to
be close in style and phrasing (though not in timing) to
the polkas which are so popular in that area.
Sorry to be droning on at such length, but this single
reel question is one that comes up from time to time when
we meet visiting musicians, and I find I'm still groping
towards a definitive answer.