Why in D if it's in G (or Em).
Why are some musical scores written in a certain key, even if they seem to belong to another? I’ve started playing traditional and early music, and many of these pieces have accidentals that could be removed by simply changing the key.
For example, with the Tourdion, if you change the key from D to G, it seems more accurate. However, in music, unusual things usually have an explanation.
EDIT: I take the time to read all your comments (I didn’t expect so much attention).
Originally, it was transcribed without a key signature, as that was the standard practice at the time.
Later, the score was adapted using a modern treble clef. And because it comes from traditional musicians who often play on D tin whistles, the score was transposed up a whole tone to match the D tin whistle.
Finaly we have : the accidental what came from ficta, and the D armor from modern notation.
Is it right ?