Thank you to everyone who posted ideas for me try to identify the windmill shown in a painting by my greatgreatgrandfather, James Sturt of Arundel and Warningcamp. From the Sussex Mills Group website I found a postcard picture of the mill. It was easily recognised because it has an unusual flat top. It was called The Cement Mill, Arundel and was built in 1864 on the banks of the River Arun and was used to grind material dredged from the river for cement manufacture. I did not realise they used mills for this. Unfortunately it no longer exists. My greatgreatgrandfather built a number of houses in Arundel and Warningcamp and probably knew the men who worked there. Ros Dunnico.