Alan and I had caught minnows in the River Roding - http://www.londonslostrivers.com/river-roding.html .
We were to use them as livebait to catch the Perch we had heard roamed the only lake we were aware of at Wanstead Flats.
It wasn't that far away, but it seemed it. We cycled to Wanstead Flats. That was where Alan suffered catastrophic damage to the frame of his bike.
Now it's a long while ago, over 50 years.
We didn't use livebait in the end - that seemed too cruel. Even for twelve year olds. I ledgered with dead minnow and caught two beautiful Perch. One was returned to the water.
The other was despatched. I'd heard that Perch were edible. It was indeed.
My mum cooked it for my breakfast the next day.
The only other time I've knowingly eaten Perch was from Lac Leman at Yvoire, with Carol.