In 1327, Willielmus, episcopus Norwich was possibly granted, by Edward III, (In year 1 of his reign) a Royal licence to crenellate palatium (Norwich Bishops Palace)

"palatium (atque omnia mansa maneriorum episcopatus sui)"

There is insufficient evidence to be certain about this possible licence to crenellate.

In Parker list as a licence by Privy Seal not on the patent roll, but I can't find where it is enrolled. (and since Coulson gives no reference other than Parker, I presume he can't either.)

Significant later source are;

• Thompson, M.W., 1998, Medieval bishops' houses in England and Wales (Aldershot: Ashgate Publishing) p167
  Coulson, C., 1982, 'Hierarchism in Conventual Crenellation' Medieval Archaeology Vol26 p93
  Turner, T.H. and Parker, J.H., 1859, Some account of Domestic Architecture in England (Oxford) Vol3 pt2 p422

More details about licences to crenellate can be found here.

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