Having said that, I am reasonably sure that the manifoil combination lock was not a standard part of the safe, but was added at some time in its life. This is based on 2 factors:
- advice from people in this and another forum;
- the fact that google image searches reveal many safes by the same manufacturer, none of which show a combination lock.
According to the plaque on the safe, it is made by "M G Dyke & Sons". Also on the plaque are the words "PIONEER SAFE WORKS RICHMOND VICTORIA".
Here is photo of the safe:

The safe is very heavy and presumably solid. That is about all I know. I would like to determine the approximate age of the safe and find a little more about the history of the company that produced it.