I am only going to (try and) post a single image for now as I know people have issues with this on here and I didnt want to spend ages writing a big post, so here goes….

it appears to be a small blue square with a question mark in it..

edit.. now some code..

OK, three attempts later and still no success in posting an image 🙁

EDIT – Yay!

The first part of the assembly….

Close up of the smaller parts

The only marks/writing on any of it.

I googled and this is the address for Coutts Bank in London which blows my theory of “something to do with watchmaking or maybe navigation” apart

And finally how I think it goes together. This is only a theory. The broken lens makes things tricky, but there does seem to be a focusing mechanism where you move the middle (broken) lens by winding the small brass ‘pulley’

The bottom lens is actually a mirror, but there are bits that seem to be exactly the right size to cover the mirror part.

The box is wood and about the size of a pack of playing cards. The metal is probably brass. I don’t know if all the parts in the box actually belong to it.

I guessed an old fashioned pocket microscope, which seems to be correct:

http://www.microscope-antiques.com/hxpocketmicro.html

That was quick. I did think of a microscope, not sure why I think forgot the idea :-/

It’s a lovely thing and was found during the house clearance of a relative. Their father was a Radiologist and had a keen interest in macro photography of flowers. That site suggests these sort of things were used by travelling botanists so it kind of tallies….

http://microscopist.net/Bancks.html

@greybeard I was just reading that page. Looks like it is at least 216 years old!

216 years old you say? Ironically, isn’t that when the method for posting photos on the forum was last updated?