Guest - I ope it didn't invalidate your presentation!

My first instrument was Harmonica, which I HAVE played for Morris and in sessions.

Very few instruments in 'folk' use today have much claim to be 'traditional' even if used for 'traditional' tunes.

Harmonica, melodeon,accordion, concertina all invented in the early 19th Century
Use of guitar very recent
Banjo - from Africa?
Fiddle 17th C

Just leaves us with bagpipe, tabor and whistle/flute, I think
Also Harp, but how often do you see one in clubs outside Wales?
'Early' instruments such as shawms do not seem to have been considered folk in UK, although they are still folk instruments in other contries.