We don't have exact dates for the Lockholes, but Lotho Sackville-Baggins took on the title of 'Chief Shirriff' after New Year III 3019, so the old storage tunnels would have first been used as prison cells early in that year. The Shire was freed from Lotho's master Sharkey (that is, Saruman) in early November of the same year, and the prisoners were released from the Lockholes immediately afterward.
Though the prisoners were freed from the Lockholes after the liberation of the Shire, the Lockholes do seem to have continued to exist in some form. There's a mention of the 'Lockholes gate' in the poem "Perry-the-Winkle" in The Adventures of Tom Bombadil, which is largely set in the Shire. That poem seems to describe events long after the War of the Ring (the Mayor of Michel Delving is there named 'Pott', so the poem must refer to a time after Sam Gamgee's retirement in IV 55, or S.R. 1476). From their single passing mention, there is no way to tell whether the Lockholes were still used to hold prisoners in this future Shire; the fact that they had a 'gate' at this point does seem to point toward that possibility, but is hardly conclusive. |