In our national parks sewage flows while the funds for conservation have run dry

To the untrained eye, Britain's national parks may look like flourishing wild spaces.

- Martha Gill

There are 15 of them, 10 in England, three in Wales, two in Scotland, and they cover some 6,000 square miles, roughly the area of Yorkshire. The Lake District, the Peak District, the Yorkshire Dales - these famous parks loom even larger in our ideas of national identity. In art and literature, the British imagination tends towards the rural.

But they are in a state. By some measures, these supposedly protected areas are declining faster than the rest of the nation. The most important bits of nature - ancient spots of woodland, open moors teeming with skylarks - are deemed "sites of special scientific interest", but only around a quarter of those within national parks are in "favourable condition", according to a report last year by the Campaign for National Parks, an independent charity. That record is beaten across England in general - where the equivalent figure is 38%. The culprits? Sheep and cows have been nibbling away at them, or they have been burned for game bird shooting, all perfectly permitted in the parks.