Although this document has been considered by some as a licence to crenellate the current opinion rejects this as a licence to crenellate.
In 1195 William de Botterell was granted permission to fortify a house at Matefelun, and received ten marks to help pay for the work. Not, in a meaningful sense, a licence to crenellate although has been called this by some.
Significant later source are;
More details about licences to crenellate can be found here.
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