It’s a stronghold for the rare red squirrel, birthplace of the Scout movement and one of the most iconic attractions in Dorset.

Yet if it weren’t for the Dorset Wildlife Trust, which celebrates its fiftieth anniversary this week, Brownsea Island could have been turned into a development of 400 homes.

Owned by wealthy recluse Mrs Mary Bonham-Christie, the island was bequeathed to her grandson in 1961, who submitted a planning application to build on the beauty spot a year later.

“Frankly,” says Nicky Hoar of the Dorset Wildlife Trust, “anything could have happened to it.”

However, thanks largely to local environmentalist, Miss Helen Brotherton (who in 1961 founded what was then called the Dorset Naturalists’ Trust) the planning application was declined.

In lieu of death duties the Treasury took Brownsea Island and handed it to the National Trust, which has leased half the island to the Dorset Wildlife Trust ever since.

“Saving Brownsea Island is still one of our biggest achievements,” says Nicky.

However, it would be the first in a long like of accomplishments for the trust – a decade later it had acquired 23 more reserves in the county, including Kingcombe Meadows near Dorchester.

“Kingcombe had been farmed traditional by same family for generations so it had these amazing wildflower meadows,” explains Nicky.

“It came up for auction, which could have gone any number of ways but we bought it and it’s still one of the top sites in the country for wildflowers.”

Their conservation work has also given a lifeline to vulnerable reptile species and birds such as the Dartford warbler, which have remained resilient in the trust’s local heathland despite a national decline.

“Our heath reserves are really important,” explains Nicky. “They are a stronghold for rare wildlife, which are important not just nationally but internationally.”

As well as providing a safe haven for wildlife, the trust has been instrumental in changing attitudes towards nature. In the last half a century it has successfully lobbied the government and garnered support for Dorset’s wildlife among the county’s inhabitants – in 2007 Chris Packham welcomed the trust’s 25,000th member.

However, its work is never done.

As well as continuing the quest to acquire more reserves, the trust also assists farmers in making their land more environmentally friendly and works closely with landowners to increase biodiversity in Dorset’s rivers.

And, having successfully pushed for the Marine and Coastal Access Act of 2009, the trust has formed a coalition with other environmental groups to establish the first protected marine reserves in Dorset.

“We are in a partnership called Finding Sanctuary, which has been working to establish where these reserves would be best placed,” explains Nicky.

“We have been consulting lots of sea users, from recreational boat owners and fishermen to offshore energy providers, to get this network of conservation zones in place by next year.

“It should reverse some of the damage done over the last few decades from things like over fishing and scallop dredging.”

l For details about the Dorset Wildlife Trust visit <&bh"http://www.dorsetwildlifetrust.org.uk/jubilee">www. dorsetwildlifetrust.org.uk