I caught a Moorhen once, fishing the LAA bank of the river Lea at fishers green.
I was floating crust under the Willow's, if I didn't get a take, i used to let the crust carry on to the bend. Just as the crust was going out of sight, I felt the line tighten and struck.
At first I thought, christ, this is a good fish, then my line started to rise up into the air, next thing the rod tip was bending upwards. The Moorhen then came towards me, only around head height.
I managed to land it and remove the hook ok, no harm to the Moorhen. Must say it was a hell of a scrap. Like so many I have also caught the Plastic bag's.