Here is my reply:
Thank you for your enquiry relating to Ashlett Tide Mill.
Tidal Mills or Sea Mills are an ancient form of watermill of
which just a few have been restored in modern times, your
nearest being at Eling, in working order.
Ashlett has not been been in operation as a grist mill since
about 1890. It was rebuilt from a former 17th century mill
in 1816 to the latest standards at that time with two
waterwheels and two sets of main gearing. As I understand
the recorded history, the earlier water wheels were removed
and a single water turbine was installed after about 50
years.
In 1920, the Drummond Estate at Cadland sold the building
and tidal pond to the new oil refinery, to allow the massive
construction works to proceed. The tidal pond of 11.7 acres
was retained or even enlarged which helped recirculate the
waste hot water from the refinery. All machinery was
removed after 1920. In 1932: the mill was leased to Esso
Recreation Club until recent times.
The sea gates or tidal gates were just north of the mill on
the dam or sea wall surrounding the pond. This controlled
the incoming tidal seawater.
There was also a storm gate or internal overflow at the
northern end of the mill, internally. It is now blocked at
the external face. The turbine water control sluice was to
the right of the centre of the mill; it is now a modern
sluice to drain the pond.