Gary Stephenson wroteone of these is 68142
Going back a bit, one possible reason for the use of brass or phosphor bronze rather than cast iron block casting which was originally to prevent the tamping of excessive amounts of gunpowder into the lock as was the use of the collar and in-out keyway - could have been that in later years when gelignite was used cast iron fragmented allowing the levers and bolt to disintegrate whereas the non-ferrous material was more malleable and tenacious.
Incidentally, this was a direct copy of Milner’s Patent Gunpowder Proof lock (1854) and used by Ratners which was founded by D R Ratcliffe, Wm Milner’s son in law in 1890. It was never known as a powder-proof lock. 69296 dates from 1963, 68254 from 1961, and 74184 from 1969, the year before Ratners ceased production as such. Long stems probably Ranalloy doors. Key retaining single keyway customer option plus less space for gelignite.
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