The River Blyth meets the sea between the pincers of the East and South Piers – long wooden structures that provide ideal spots for anglers. It is sunny and warm, with sufficient breeze to propel the occasional sailing boat out of the sheltered harbour onto the gently swelling sea. Wind turbines, evenly-spaced along the East Pier, rotate slowly. With the demolition of the power station, the final emphatic industrial landmark has gone.

Above Furnace Bridge, Bedlington, a path ambles by the river through remarkably pleasant woodland, filled with birdsong and the sound of rushing water. The river seems surprisingly youthful, both narrow and shallow, given that it is merely two miles to its mouth. Here is a steel sculpture of the Roman god, Janus, on the site of Bedlington Ironworks, which closed in 1867. It is almost inconceivable that this was once an industrialised stretch of riverside, its transformation is so complete.

Giant stepping-stones cross the river near Humford Mill. Then, the Horton Burn trickles in, beneath a roof of foliage that creates a cool, green, shadowy dean, dappled light playing on the water. New growth is luxuriant, almost jungle-like in its density. A tiger creeping through it would not be out of place (except geographically) as in a Rousseau painting. A heron takes flight in elegant slow motion. A female mallard swims away, six chicks trailing in her wake.

Suddenly the path narrows between thick stands of shoulder-high bracken, connected by filaments of spiders’ webs that break gently on your face. A rocky outcrop reveals wavelike strata, overgrown with ivy and topped by precariously-perched trees, their twisted roots exposed. Here the path vanishes, forcing you to cross the river by stones. A weir channels the river through what once must have been a gated chute.