In this feature we look as an extract from David’s book “The Key to Lock Picking” on page 12.
It shows in black & white photos of a very old prison door lock. The one in question is the Charles Smith & Sons prison / asylum lock. Here is an insight in to this part of David's book.
The lock its self is very large measuring 26x18 cm and it weighs 4KG. David states the lock dates to about 1870, this is close in fact it was manufactured from 1867. It was in use apparently in a cell near David from 1874 to 1978. I personally know that once Douglas Police Station in Scotland had this type of lock and was in use right up to approx 1984. So gives you an idea of how trusted and mechanically reliable this was to be used for this period of time.
Left: David's Photos from his book.