At various points along the banks of the canal, there were flowers. Some, like the cow parsley, were obviously wild, but I suspect that others had been introduced deliberately.
These, I am almost sure, are yellow flag irises. Mum was a keen gardener and one of the plants I remember in our garden was the blue flag iris. These look just the same (except for being yellow of course).
The Latin name is pseudacorus and they are, supposedly, easy to grow. They prefer moist or boggy ground in full sun or partial shade and can reach heights of up to 120cm. I think I prefer the blue to the yellow, but they have a beautiful shaped flower with large droopy petals, and looked glorious standing tall and bright between the towpath and the water.
By the way, if any American readers stop by today...