Round Island, Poole Harbour: From Country Estate to Wartime Training Ground

Nestled in the heart of Poole Harbour, Round Island is one of Dorset's most distinctive private islands. While today it is known for its peaceful setting and unique character, its history tells a remarkable story of architectural ambition, wartime service, and generations of careful stewardship.

Until 1935, Round Island formed part of the historic Rempstone and Wareham Estate, passing through the Ryder and Marston families following the death of William Montagu Calcraft in 1886. The island remained largely undeveloped until the mid-1930s, when a new vision transformed its future.

In December 1934, planning permission was granted for what would become the island's principal building, the Main House, with a Gardeners Cottage by the Pier.

The Main House was completed in 1935 to designs by the renowned architect Sir Edward Maufe, best known for Guildford Cathedral. Built by H. J. Hillman of Canford Cliffs, the project also saw extensive tree planting across the island, helping to create much of the landscape visitors recognise today.

One particularly intriguing detail is that planning approval for the pier was not granted until April 1935. This suggests that the materials used to build the Main House had to be brought ashore via a small channel elsewhere on the island before being transported across the site.

The most significant chapter in the history of Round Island came during the Second World War. Requisitioned by the military in 1940, the island became part of HMS Turtle, the Royal Marines base at nearby Hamworthy. It served as a training ground where coxswains learned chart reading and navigation, while Officers were accommodated in the Main House. Remarkably, the house survived the war largely untouched, with a surviving bomb shelter providing one of the few visible reminders of the island's military role.

Following the war, Round Island changed hands several times before entering its current ownership in 1968. During the late 1950s and early 1960s, a number of improvements were made, including the reconstruction of the pier, installation of a water tower, construction of a boathouse, and extensions to existing buildings.

All buildings on the Island pre date our ownership.

Today, Round Island remains one of the most unique private islands in Poole Harbour. Its history reflects not only the changing fortunes of a remarkable Dorset property, but also its place within the wider story of Poole Harbour itself—one of the world's largest natural harbours and a location rich in maritime heritage.