One thing I should have mentioned in the article, the Lea is FULL of Signal Crayfish.
From a fishing point of view they are a complete nightmare, eating anything that comes withing range, soft baits don't stand a chance.
Even Hard baits such as Boilies and Pellets have to be checked every half an hour if you are fishing areas with high populations of Crayfish.
And those area's are the soft bottom parts of the rivers and lakes that have the Lea running through them.
The good thing is, all species of fish like eating Crayfish and they now seem to form part of the staple diet of Chub, the main reason I believe the Chub of the Lea system have grown so big in recent years.
Leading around is well known to Carp anglers as a way of feeling the lead as it drags over the bottom and is trasmitted through the line to your rod tip and fingers.
It gives you an idea of the bottom type you are fishing over, be it silt, clay, or gravel and the contours of the bottom.
From experience, finding areas of clean Gravel on the river bed has one distinct advantage, the Crayfish don't like it and even in predominately clay and silt parts of the river, finding small areas of gravel gives an angler a better chance of keeping his bait in the water for longer without the attension of Crayfish.
This was one of the things that gave Simon and I an advantage, we would always lead around in new swims to find the Gravel spots.
If we had trouble with Crayfish, often it was down to not being on the gravel outcrops, which can be quite in small, maybe a metre or so in size.
If the Boilie did not land on on the Gravel it would go missing along with the hair and boilie stop in a matter of minutes, find the gravel and the boilie would still be there in hours !!
Bob