The original mill was built in 1886 and closed in 2000. Peat was removed from the moors and milled and bagged here before being taken to the Ouse for export as animal bedding.
After the Second World War peat was used by the horticultural industry and later extracted in increasing intensity before environmental concerns brought the enterprise to an end. For more detailed information on the mill see Swinefleet's Wikipedia page.
The outside shell of the building has many holes, and there's little inside except girders and a short processing shaft, which is possible to inspect.
Here are some photos of the visit:
Main platforms
The girderage and walls provided decent climbing practice
Finally, here's an experimental YouTube video of the visit using the "Video Star" music video app (unfortunately will only open on desktops and tablets).