It is thought to have been first built circa 1627 as this date is carved on part of the framework.
This is the earliest date to be found on any windmill in the British Isles.
It should be remembered that such a structure would have had to have frequent repairs made to it, so it is quite possible the mill predates 1627.
It was dendrochronologically dated in 2004 by Dr Martin Bridge of the Oxford Dendrochronology Laboratory, when the oldest pieces in the buck were found to be from trees felled in winter 1595/96 and spring 1597.
The 'new' crown tree was made from a tree felled in spring 1670, while the quarter bars of the trestle were from trees felled between 1824 and 1826, so like most mills it is a mix of old timbers variously recycled or hanging on from their original use.

For many hundreds of years grain grown in the two adjoining villages was ground at the mill into flour.
In 1874 the mill was bought by Adelbert Wellington Brownlow Cust, 3rd Earl Brownlow who owned the nearby Ashridge Estate.
He subsequently let it to a local farmer, who ran a successful milling business from the mill.

In 1902 the mill was seriously damaged during an enormous gale, damaging it beyond the price of economic repair.
Around 1922 the derelict ruined mill was bought from the Ashridge Estate by a farmer whose land was close to the mill.
In 1937 he donated it to the National Trust.
However, it was not until 1963 that a band of volunteers began to carry out renovations at their own expense.
The mill appeared in an episode of The Champions titled The Invisible Man which was filmed in 1967.
In 1970, after an interlude of 68 years, the mill once again ground corn.

Today the windmill is open to the public on Summer Sunday afternoons.
It is thought to have been first built circa 1627 as this date is carved on part of the framework. This is the earliest date to be found on any windmill in the British Isles. It should be remembered that such a structure would have had to have frequent repairs made to it, so it is quite possible the mill predates 1627. It was dendrochronologically dated in 2004 by Dr Martin Bridge of the Oxford Dendrochronology Laboratory, when the oldest pieces in the buck were found to be from trees felled in winter 1595/96 and spring 1597. The 'new' crown tree was made from a tree felled in spring 1670, while the quarter bars of the trestle were from trees felled between 1824 and 1826, so like most mills it is a mix of old timbers variously recycled or hanging on from their original use.
For many hundreds of years grain grown in the two adjoining villages was ground at the mill into flour. In 1874 the mill was bought by Adelbert Wellington Brownlow Cust, 3rd Earl Brownlow who owned the nearby Ashridge Estate. He subsequently let it to a local farmer, who ran a successful milling business from the mill.
In 1902 the mill was seriously damaged during an enormous gale, damaging it beyond the price of economic repair. Around 1922 the derelict ruined mill was bought from the Ashridge Estate by a farmer whose land was close to the mill. In 1937 he donated it to the National Trust. However, it was not until 1963 that a band of volunteers began to carry out renovations at their own expense. The mill appeared in an episode of The Champions titled The Invisible Man which was filmed in 1967. In 1970, after an interlude of 68 years, the mill once again ground corn. 
Today the windmill is open to the public on Summer Sunday afternoons.
Pitstone Windmill