I have just had passed on to me, a set of variations for wind band, of the Londonderry Air. The arrangement is extraordinarily beautiful, but I've never heard it before and do not know who composed it. Neither did the person who passed it on to me. I have a suspicion it might have been Percy Grainger, although various googlings bring up only the choral setting he made of that piece. I wonder if anyone out there might know for certain.

Two clues. 1. It's about four and a quarter minutes long. 2. About three minutes and forty five seconds in, it rises to a great crescendo and the crescendo is reinforced with a cymbals clash.