An incredibly desirable plot of land worth £20million on the exclusive Sandbanks is 'highly unlikely' to ever be sold due to a covenant put in place 100 years ago. 

The one acre plot, on which two luxury mansions could be built, is currently home to a tumbledown cottage, a tired-looking boat shed, a pavilion and a tennis court. 

It is one of the few pieces of land on the celebrity hotspot peninsula in Dorset which hasn't been built into a contemporary mansion or a swanky apartment block. 

That is because of a historic covenant which means the property will almost certainly never change hands - despite a host of developers putting forth lucrative offers to the owners. 

The land is held in a family trust that was set up by millionaire businessman Dr Edward Andreae in the 1920s.  

Dr Andreae, of German descent, was one of the first major landowners on Sandbanks at a time when it was merely barren, windswept headland.

He had individual homes built there for all eight of his children and also snapped up the large site on the northern shore to use as a recreation space for his wider family. 

Over the years the homes have been sold and their plots redeveloped but the site at 16 Panorama Road has remained in its trust - and can only be sold if every member of the family votes in favour. 

The Andreae family now numbers around 100 people, meaning it would be near impossible for such an agreement to be reached.

Locals say family members still use the site and come together there every summer. 

The average price of a property on Sandbanks is just under £1million and the exclusive neighbourhood has been a home to stars such as Harry Redknapp, John Lennon and Liam Gallagher in the past.

Sandbanks historian Jeremy Waters said: 'The Andreaes were Lutheran Germans who came over here in Victorian times. They were related by marriage to Kleinwort Bank.

'It was while Edward's brother was sailing his huge yacht into Poole Harbour that he discovered this delightful place called Sandbanks. It was completely unspoiled.

'Edward took his growing brood of children for summer holidays there. He used to run a factory in Flintshire that made artificial silk and sold that and made a substantial sum.

'He then did very well buying up failing companies, breaking them up and selling them off. I have seen family photo albums and it was all stately homes, Rolls-Royces and hunt balls.'

During the late 19th century, it was found that sea defences were urgently needed to stop the Sandbanks peninsula being split in two by erosion.

The land belonged to Lord Wimborne but he did not want the expense of the work and instead offered the Poole Harbour Commission the opportunity to buy it for a nominal fee provided they paid for the sea defence works.

The commission sold off 40 plots of land on Sandbanks for development at a public auction in Poole.

After the First World War, Dr Andreae became Sandbanks' first property magnate by building the eight homes on the peninsula.

Mr Waters said: 'Six of them were on one side of the road and three on the other side, including the land at 16 Panorama Road.

'All but one of the houses have since been sold off. The plot of land that is left is a joyous relic of Sandbanks as it used to be.

'It is virtually untouched and uncommercialised. There is a small cottage, a tennis court, a boat shed and a pavilion near the water's edge.

'It was and still is entirely for the pleasure of the family. It is in a family trust in which all members have an interest and they now number almost 100.

'There has to be a very high percentage agreement before any change of ownership can happen which is highly unlikely.

'I don't expect they can all agree what time to have coffee let alone sell it.'