Bourn Mill dates from 1639. The mill is an open trestle type windmill, a design hardly changed since the 13th century. The orientation of the mill is changed to catch the wind by means of a tailpole from which the steps are suspended, enabling the whole mill to be rotated around the main post. The building is Grade I listed and is also a scheduled ancient monument.
In 1985 rhp worked with the Cambridge Preservation Society on a scheme to bring the mill back into working order and received a Europa Nostra award for the sensitivity of the repair work. More recently a quinquennial inspection revealed the need to repair the stocks and sails, and grant aid was obtained from the Heritage Lottery Fund in order to undertake these works which were completed in 2003. In 2009 the trestles were repaired and the trestles, buck and sails redecorated.