We had a Norfolk Terrier when I grew up. Tied a few muddler type flies. Worked a treat on stocked rainbows - they looked like trout pellets.
Veniards back in the 1980’s paid 50p per grey squirrel tail. That was good money in those days.
Decline in Trout fishing probably directly in relation to number of rivers that hold decent stocks of fish. I used to fish the Windrush 30 odd years ago - it was a beautiful river with wonderful meadows with fritillaries and good stock wild browns and barbel, with lots of beautiful weed and crystal clear water. Ducklington Angling charged £30 or so a year. Certainly not expensive for a student.
I went back there a few weeks ago. The meadows are now housing estates, and the river stinks like a sewer.
Up here in Edinburgh where I now live all the local rivers used be full of trout, grayling and a few salmon. Permits were inexpensive or free, abd plenty of fish to catch. Again they are now sewers.