The Westminster and Middlesex Commission of Sewers was established in 1596 under the 1531
Statute of Sewers.
Its area was defined by statute in 1807, and before then by various
letters patent
Letters patent ( la, litterae patentes) ( always in the plural) are a type of legal instrument in the form of a published written order issued by a monarch, president or other head of state, generally granting an office, right, monopoly, titl ...
.
It was absorbed by the
Metropolitan Commission of Sewers on 1 January 1849.
References
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History of local government in London (pre-1855)
Water supply and sanitation in London
Former water company predecessors of Thames Water