Yes, an informed post starbird. There's more to flood management than most people realise. Straightening and deepening rivers is not always the answer. Under some circumstances dredging is the right thing to do, but not always - it is very complicated.
The old-style farmer and landowner knew their rivers, streams and ditches, and how to manage them, but this knowledge, handed down through the generations is being lost due to changes in farming, land ownership, etc.
Meanders, which created mini flood plains, slowed the flood water down and were a refuge for wild life, these have indeed been removed and streams 'straightened'. I witnessed such a project about 20 years ago where the stream was straightened to run alongside a new road and the reclaimed land used for housing. The road now floods regularly and it's just a matter of time and luck before the houses are inundated too.
Yes, the fells have always been used for grazing sheep, but not to the extent they are these days. Tree planting, absolutely essential, and the 'right' kind of trees too.... and so it goes on.
There are myriads of small 'fixes' that need to be addressed, in addition to the big ones and actual 'defences' - which is what I meant in my previous post about 'joined up thinking' - but it's simply not happening.