UK coastline has seen 42% rise in urban, built-up environments over 50 years
An area of the coastline the size of Manchester has become built up in the past 50 years, a mapping project across England, Wales and Northern Ireland has shown.
But the new survey for the National Trust, updating coastal mapping first carried out for the organisation half a century ago, has revealed that three-quarters of the countries' coasts are still undeveloped.
And 94% of the 3,342 miles of coastline considered to be "pristine" in the original survey in 1965 is now protected, as it is either owned by the National Trust or is designated as an important natural area in the planning system.
The National Trust looks after 649 miles of the coastline identified as pristine in 1965, which along with designations including areas of outstanding natural beauty, national parks, heritage coasts and sites of special scientific interest mean most is protected.
The Trust first commissioned students from the University of Reading in 1965 to survey how land was being used along the coast, as part of its newly-launched Neptune campaign to conserve coastlines which has helped it buy
New surveying undertaken by the University of Leicester compares the situation now with the findings 50 years ago.
It revealed that there has been a 42% increase in urban and built environments along the coast over the past 50 years, an increase of 17,557 hectares (43,400 acres), an area the size of the city of Manchester.
There has been a 39% increase in the amount of industrial land to cover 13,081 hectares (32,300 acres), although there has been a shift from quarrying and mining industry to more ports and areas with storage containers.
There has also been a decline in the amount of land used along the coast for defence, with 4,209 hectares less used for the purpose than 50 years ago.
Overall 76% of the coastline of England, Wales and Northern Ireland remains undeveloped, providing an important resource for people and nature, the National Trust said.
The survey suggests the planning system has worked well to protect the coasts, but the Trust warns that pressure for offshore development such as wind farms means the challenges facing seascapes is much greater.
Peter Nixon, director of land, landscapes and nature for the National Trust, said: "50 years after we launched our Neptune campaign, most of the UK coast remains undeveloped.
"Our coastline has been spared the sort of sprawling development that other countries have suffered.
"This is a moment to pause and celebrate the generosity and passion of our supporters, and the value of a robust planning system in securing a coastline that people can access and enjoy."
He said polling showed 90% of people agreed it was important for the planning system to work to protect the coastline.
He added: "We must also look out to sea where the challenges are now much greater. As the need for offshore development increases, the new marine planning process must be as effective and rigorous as the planning system on land has become."