NavList:

Dave,

I agree with your suggestion of the interpretation of the certificate. I have one of those 3½" sextants, number 31324 with certificate dated 16/4/45 and signed by the same person, or rather that person's name is stamped on the certificate. The corrections to be applied is stated as -1', -1', 0' for 30°, 60°, 90° respectively. Although the scale goes as far as 120°, the upper limit is actually 101°45'.

My father bought the sextant some 50 years ago from an older yachting friend who claimed it was a "lifeboat sextant", thus the small size. What was the intended use in RAF for this small sextant? 

This sextant is very handy and I really like it. I have used it for most of my sights for the last 25 years (not too many, though).

Lars, 59°N 18°E

I'm really kind of interested in this sextant, I like undersized tools for some reason.  I have a collection of pocket sized (6" or smaller) slide rules.

Whatever.  What is the power of the scope?  How hard would it be to fit a new horizon mirror since the one in the auction item is missing?

Actually what I would like to get hold of is a FrancisBarker Small yacht sextant.  Had the chance to get one when I was in college but got a CD player instead.  My bad.