WHAT defines — or delineates — an island nation like ours? It has to be the coastline. Nobody in Britain lives more than about 80 miles from the dolphin-torn, gong-tormented, dragon-green, luminous and serpent-haunted sea — a moat defensive to a house against the envy of less happier lands, built by nature against infection and the hand of war.

This year is the bicentenary of the battle of Trafalgar, the apotheosis of Britain’s maritime mastery. A highlight of SeaBritain 2005, a year-long celebration of our maritime past, present and future, is the photographic exhibition The Coast Exposed now on show until January 8, 2006, in the 17th-century Queen’s House at the National Maritime Museum, Greenwich.

The National Trust Photographic Library and Magnum Photos are showcasing the natural wonders of the coast, the environmental pressures it faces and the British people’s continuing fascination with the sea.

Splendid seascapes, both rugged and placid, contrast with minute and colourful objects to be found underfoot on any beach, rock pool or shingly spit — sea shells, seabirds’ eggs, starfish, whelks, wrack and weed. Magnum, created in 1947 by Robert Capa, Henri Cartier-Bresson, George Rodger and David Seymour, has a particular forte in the evocative black-and-white shot — the stark Giant’s Causeway in Co Antrim, a friendly beach opposite the Ty Coch pub at Porth Dinllaen, North Wales, and the tragic events at Boscastle.

There is naturally a strong emphasis on the work of the National Trust. Fiona Reynolds, director-general, remarks that the National Trust now owns 700 miles of Britain’s more vulnerable coastline, including 60 per cent of that surrounding Devon and Cornwall. Many shots are of their wardens repairing cliff edge fences, counting seabirds, informing the public and, for example, helping the 120,000 annual visitors to navigate the Carrick-a-Rede rope bridge to Carrick island over its 24-metre chasm. “The National Trust is attracting about 100,000 new members every year — this is tremendously encouraging for our heritage and environment,” Ms Renolds says.

But there is a down side. One of the exhibits shows the rubbish collected from Studland Bay in Dorset. “Would you believe,” says a National Trust volunteer, “we pick up abandoned plastic buckets and spades bought that day from the beach shop.” It costs £80,000 a year to keep Studland Bay clean and takes 80 per cent of staff time in summer, 15 per cent in winter. Sixty tons a year are collected. A Marine Conservation Society study used 3,000 volunteers to trawl 269 beaches in September and concluded that beach litter has become 80 per cent worse in ten years, with 1,100 non-biodegrading plastic items found per kilometre.

Perhaps this exhibition will cause the sense of pride and responsibility that is so evident among National Trust workers to be rooted more firmly elsewhere.

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