When composers began writing for the particular capabilities of the Böhm flute (developed by Theobald Böhm around 1850 that eliminated cross-fingerings by putting a hole for every note of the chromatic scale, sited at the optimal location on the tube, and making these holes very large) came, all the old wooden flutes began to show up in pawn shops for low prices, where the Irish began to buy them.
The so-called Irish flutes are a Nicholson-type flute that was popular and relatively expensive in early 19th-century England. It seems to have first entered Irish traditional music, joining the fiddle and Uilleann pipes, about a century later, when its market value had fallen almost to nothing.
Irish players value the Nicholson-type flute's strong tone, especially in the first octave, but they generally don't use its keywork, preferring the effect of fast finger movements on the open holes. They tend to play in the keys of D and G rather than the flat tonalities such as F, B flat, and E flat, the original makers and players enjoyed.
Flutes currently made for Irish music usually follow the pattern of the 19th century wooden flutes with large holes, except that the instruments have only a few keys, or none at all. The resulting instrument, not quite a baroque flute and not quite a 19th century classical flute, is often called an "Irish flute".
Today the basic Irish flute is a simple system six hole flute tuned such that the lowest playable pitch (all holes closed) is the D above middle C, and the instrument will play a D scale (D, E, F#, G, A, B, C#) as the holes are uncovered sequentially to shorten the resonant length of the pipe. The basic flute can be played in the key signatures of D and G without difficult cross fingerings, which is sufficient for a large variety of traditional Irish melodies.
The Irish flute may be embellished with the addition of keys (typically metal, mounted to wooden blocks) used to play pitches which would require cross fingerings or be impossible to produce on the basic flute. Four keys (short F, G#, Bb and Eb) are required to produce a fully chromatic instrument. Two keys (long F and high C) can be added to improve playability, and two more keys (low C and C#) can be added to extend the range of the instrument to middle C.
IMPORTANT NOTICE! Health and sanitary regulations prohibit the exchange or return for credit of any mouth blown instrument.