'Quiet please' for green city boost

But the findings boost Sheffield's reputation as one of the nation's greenest and most rural cities - nearly 30 per cent of it remains undisturbed by noise and visual intrusions.

Less than four per cent of the suburbs of Leeds have a similar rating, while other Yorkshire cities like Wakefield and Hull have virtually no quiet areas at all.

The findings from the Campaign to Protect Rural England show that countryside free from major disturbances is disappearing fast - and could all but disappear in most regions of England by the end of the century.

Urban sprawl has affected Sheffield too - in the early 1960s 55 per cent of land in city boundaries remained undisturbed, compared with more than 70 per cent now.

Rotherham is the most urbanised authority in South Yorkshire, with less than six per cent unaffected by noise compared with more than 32 per cent 45 years ago.

Worst affected over the last few decades has been the Barnsley area, once the most unspoiled in the country with less than 52 per cent undisturbed. Now the figure is more than 89 per cent.

In Doncaster more than 87 per cent of the authority is affected by disturbance, compared with 59 per cent in the early 60s.

Nationally the picture shows that half of England is disturbed by major roads, urban areas and other large developments like power stations and airports.

The Yorkshire region is becoming increasing urbanised, especially over the last 15 years, although there are nearby national parks like the Peak District, the Yorkshire Dales and the North York Moors.

The CPRE says that since the early 90s an area the size of Greater London has been lost to urban intrusions every two years.

At this rate most of the remaining undisturbed countryside could be blighted over the next 80 years, it adds - and says the rate of loss is increasing.

"As the shadow of intrusion stretches further and wider, the peace and quiet we need is harder to find," said CPRE chief executive Shaun Spiers.

"Development of all kinds fragments the countryside, undermining the qualities of tranquility, openness and immersion in the rural landscape which people most value about it," he added.

The research has been done by comparing maps from the early 60s and early 90s with new maps and data for 2007.