If you are going through boxes of old family papers you will sometimes find ephemera - i.e. documents which would normally have ended up in the waste paper basket. It is worth wondering why they have survived - as to be in the box one of your ancestors must have thought they were worth keeping.
In this case three names are mentioned, George Nettleton, George Gaffe, and William Cartmel. But who were the instrumentalists, and if the concert was reported in the local newspaper it might have listed the people involved, including some to the leading citizens who attended. Maybe one of your ancestors was involved.
So if you find a very old document that you don't understand I suggest that you try and work out why it was kept in the first place - and you might discover some new information for your family history.