Here might be a good place to start. William Hill has pointed out that there are 1780 mill paintings only a click away.
They are part of the national collection of paintings. They have been published on the web by “Your Paintings”, which is a joint initiative between the BBC, the Public Catalogue Foundation (a registered charity) and participating collections and museums from across the UK.
To see the 1780 (which will grow as more are added) click here and enjoy.