We have records of only a single member of the Brownlock family, and for her we have no specific dates. Nonetheless, we can say at least something about the dates of the family, because Gilly Brownlock (its only named member) married Posco Baggins, who was born in III 2901 (S.R. 1301). So, Gilly must also have been born near the beginning of the fourteenth century of the Shire-reckoning. We also know that she attended Bilbo Baggins' Farewell Party in III 3001 (S.R. 1401), when she must have been approximately a hundred years old. Gilly and Posco had three children and many descendants, but those would have carried the Baggins name, and it is unknown whether the Brownlock family persisted after this time.

The name 'Brownlock' is not formally defined by Tolkien, but the interpretation of 'lock' as referring to a lock of hair seems inevitable. Certainly this is the origin of 'Brownlock' as a real family name, and we also have a comparable use in Goldilocks ('golden-haired'), the name given by Sam Gamgee and Rose Cotton to one of their daughters. Also comparable is Leaflock, 'leaf-hair', the name of an Ent whose Elvish name Finglas contains fin-, meaning 'hair').