Sorry!, not really an oversight, I rushed to get the St Pats answers on in case anyone was looking to use a quiz on the Eve, or on the day.

Herewith Instruments. (including atrocious puns at 10, 15 & 20)

1,Die Zeiberflote / The Magic Flute
2, Mr Tambourine Man
3, Zither
4, Mouth organ / Harmonica
5, Bagpipes (played by Scotty)
6, Harp
7, Bodhran
8, Flute (the Galway in question being James Galway)
9, Lyre
10, Harpist
11, Xylophone
12, Fife
13, Horn
14, (Brake) Drum
15, 'Obo(e)
16, Cornet. (Several responses of Tuba, which I decided to accept, as in a Tub'a ice cream)
17, Virginal
18, Trombone
19, Belle
20, Saxophones (Groan!!)