It looks like it would be used to connect pieces of paper without a stapler/staple.

Staple-free stapler.

https://www.containerstore.com/s/office/office-supplies-accessories/staple-free-stapler/12d?productId=10034730

Thanks so much we weren't sure if it was old or not as dad is a collector of many things

There are lots of old paper fasteners out there....I think yours is one of the older ones>
https://www.officemuseum.com/stapler_gallery_stapleless.htm

Thanks so much ☺