Fitting a night latch lock, the video instructions on this page detail not just the fitting of a standard night latch, but fitting night latches to non standard installations. Often these very popular locks need a bit of TLC from time to time and likewise the second video details how to repair night latch installations.
There are two videos, one which deals with fitting a night latch where the installation is straight forward and is a little over 11 minutes in length. The second more comprehensive video which details the non standard installations and repairs to previous night latch installations and is just under 22 minutes long.
Below is a short trailer for the second more comprehensive video.