Anyone know what these "sticks" are called?

[voodoopenguin]

Still occasionally going through my late mother-in-law's effects and have found these three sticks. They appear to be made of a very hard wood, are perfectly cylindrical and one has a label "Approved for Government". Apart from that one label they are unmarked. I don't think they are police batons but after measuring them I am wondering if they are some sort of standard measuring device as the two shorter ones are exactly 12" and the other is exactly 18" in length. Hopefully, even though I am in the UK, there will still be someone who will pipe up with a "I know what they are!"

Paul