Unimaginatively, I usually take the same route for a morning walk when on holiday in Cornwall, over the dunes to Brea Hill, inspiration for Betjeman’s poem ‘Back From Australia’. I know the scenery so well I no longer see it.

But for a change the other day I walked along the other side of the estuary and it was like seeing an entirely new landscape: the gently scalloped sandbanks, the clarity and blueness of the water, the breadth of the sky where it met Pentire Point.