E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Licence. Shakespeare says. Sir John, you are a gentleman of excellent breeding, of great admittancei.e., to whom great freedom is allowed (Merry Wives, ii. 2). The allusion is to an obsolete custom called admission, by which a prince avowed another prince to be under his protection. Maximilian, Emperor of Mexico, was the admittant of the Emperor Napoleon III.