Christies will be auctioning various items belonging to the late Baron Swaythling (https://en.wikipedia.org/wiki/David_Montagu,_4th_Baron_Swaythling) and amongst them are some lovely jewels, including no less than 4 tiaras which include a stand out Koch tiara.

https://www.christies.com/en/auction/the-collection-of-the-late-lord-and-lady-swaythling-29663/?filters=&page=1&searchphrase=&sortby=lotnumber&themes=3580786

Koch tiara

https://www.christies.com/lot/lot-6367952?ldp_breadcrumb=back&intObjectID=6367952&from=salessummary&lid=1