A-sol, a-sol, a sol-dier I shall be
For King, For king, For King and count-er-ree
Fo' cur, Fo' cur, Fo' cur-i-osity..
Fight for the old count, fight for the old count, Fight for the old count-ry

Leastways, that was how we sang it in the Sealed Knot, one of the English Civil War societies, normally before keeling over helpless with laughter. Normally about three o'clock in the morning and a couple of bottles of mead worse for wear. As for coming from something operatic, I haven't heard of it but I would be fascinated to know more....