Right now I am trying to learn "Nancy" from the 1,2,3 book but can't find the tune I the internet.
A beautiful tune, written by the late Tom Clough for his wife Nancy, if I have the story right. I learned it on the whistle -- from the Northumbrian Piper's Tunebook -- before I took up concertina. Two parts straight, followed by quicker variations (i.e., with more notes) on those same two parts, which variations I understand were also Tom's. I sometimes do it a third time through, with a few additional diddlies of my own.
There are plenty of versions on YouTube, in a variety of styles and many with at least a couple of notes different from the version in the NPT. Here's one version on fiddle that's pretty straight and more or less in the style I remember from Alistair Anderson's playing, though I think a tad slower. And here's a quicker take with Nancy Kerr -- someone who should know the tradition -- on fiddle. Nice, though I feel the guitar tends to overpower the fiddle in the quicker parts, making it hard to hear just what's happening in the melody.
What I believe I remember from Alistair's solo playing is a speed between the above two examples. On the other hand, aside from the version by the High Level Ranters, of which Alistair was a member, I remember him saying on one occasion that "in Northumberland, the dances start off at breakneck speed and accelerate from there."