The Clicker 1460 from Velos, a measuring device for maps, the 1460 cost 1/- when it was originally sold. I have the original box which is quite tatty, the paper insert (pictured) which has the instructions.
Written on the handle of the Clicker is:
The Clicker 1460 - Patent 422611 - British Made - Map Mile Recorder
and on the reverse
For any scale maps - Example, 1 inch scale - 4 clicks to 1 mile.
My Garmin GPS makes this job easy now but I used to use this when I started walking, it was a big improvement on a bit of string!
IWC's blip made me dig this out of the drawer for a picture