Great Scott Antiques
Web site: https://www.greatscottantiques.com/
At first glance remarkably similar to the bullet pencil found in the Princess Mary gift tin, this example is made from a WW1 Turkish Mauser cartridge.
The "bullet" pulls off to reveal a pencil. It is possible the bullet is silver, but I have not rested it as such.
A handsome item, and the only one of its type I have ever seen.