Fish in Lucy Brook?

This morning I saw a heron quietly hunting along the banks of Lucy Brook, at the back of the Aldcliffe gardens, just to the south of the old Oak tree. Probably the one Drip commented on yesterday. It stared intently into the brook, and after a few minutes darted its beak into the water. There were two flashes of silver from around its beak and the heron retreated back from the edge – to digest something? Had it actually found a fish? It moved on a little, and got something else, more from the opposite bank than in the water. Unfortunately too far away and too many intervening branches and leaves to get a clear view. But again it appeared to have found food, possibly entangled in some twigs – a frog? After a while it flew off through the Hay Meadow, and appeared to sweep back to land further down the course of the brook.