In the early years, coal was removed from the colliery site by boats, which approached the quayside at high water. However, the changing river bed meant that a partial canal was dug to ensure safe passage.
Records show that Thomas Cowper and Richard Mason of London leased Mostyn Colliery in 1594.Records suggest that by the 17th century Mostyn was possibly the largest colliery on the Western seaboard of Britain. It certainly seems to have been the most profitable in the North Wales coalfield.
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