I have been working on some Mill Dimensions which should help us pinpoint where to open up next to map the footprint. It isn't easy to be very accurate as the zoomed in lines of the OS map are nearly half a metre across!! Anyway it will put us more or less in the correct area of our next point to be excavated.
I have also worked out some rough distances from the mill to some of the ancillary buildings down by the river where we will need to put in some test trenches to confirm their positions during the development phase. Weather permitting we should be able to start that fairly soon.