The keylock has been used in one form or another since it's invention in ancient Egypt some four thousand years ago. The Romans made keylocks of essentially the same design over a period of hundreds of years, keys for which are still being found to this day. It was not until the industrial revolution that the security of locks became less dependent on wards and real improvements in security took place.

The first major improvement took place with the invention of the 'Double Acting' lever by Robert Barron in 1778. Up until this point it was only necessary to bypass any wards and then lift the lever or levers to open the lock.

A warded safe key - circa 1750

boxwardskey

Now with the double acting lever a lever lifted too high was as secure as a lever not lifted high enough. A good Barrons lock could havBarron'sber of such levers, all of which would have to be lifted to the correct height at the same time in order to open the lock.

Many patents were taken out for locks in the years following Robert Barrons patent, two ofBarron'sst technically important being the Bramah lock in 1784 and the Chubb detector lock in 1818.