Brownsea Island is situated in Poole harbour, Dorset, England and is the largest of eight Islands.

It has played an important part in the coastal defences of England and in providing warnings to shipping. It's earliest known history is of a hermit living on the island 1400 years ago who would light beacons at the north of the Island to warn boats entering the harbour.

It was fortified by Henry VIII who began the building of the castle. It originally had walls 40 feet long and 9 feet thick and was moated on three sides with a gun platform on the seaward side. The castle was added to during the English Civil War when it was a parliament stronghold.

The owners of the castle and the island have given it a chequered history. One owner was responsible for war with America, and the near invasion of Canada. He ended his days living on the island before committing suicide in the Castle. Another owner was a spendthrift who invested most of his money in the china clay that was to be found on the island. Unfortunately it proved to be useless and he lost his investment but not before lavishing £10,000 on the beautiful church which still stands today.

In 1896 the castle had electricity installed and soon after caught fire. In rebuilding, some features were removed such as some of the turrets but the castle still retained quite a lot of character.

In the 1930's a Mrs Bonham-Christie turned the island in to a bird sanctuary and banned all visitors to the island. While her intentions were good the end result was the island becoming overgrown and the castle almost ruined. After her death the National Trust came to the rescue and purchased the island. Part of it was reserved for a bird sanctuary and the rest was opened to the public. A handful of cottages still remain which house National Trust staff or are leased out.

The castle and it's grounds were leased from the National Trust by the John Lewis Partnership, who renovated the building and use it as a holiday destination for partners of the business during April to October. These are not open to the public.

In 1907 Lord Baden-Powell held the first boy scout camp on the island and a commemorative stone still stands on that spot today. It has become an unusual summer Mecca for groups of adults and children wearing shorts and woggles.

One of the most startling sights on the island are the peacocks that roam wild. They are noisy and can be vicious but are beautiful during July and August when they fully display their tails. The island is also one of the last remaining homes in the south of England of the red squirrels which frequently carry out raids with the help of the peacocks on the afternoon teas served on the castle terrace.

On a number of occasions the rabbit and deer population have increased above the level that the island can sustain and so they have been removed or destroyed. However the tides between the island and the mainland can become so low it is not unusual to see rabbits and deer swimming/paddling their way back to the island.

The island can be visited by catching a National Trust ferry from Poole Harbour.