I just won a second hand doublet on eBay and need some help sorting out options for wearing it. Not that I need another kilt jacket, but I didn't own a doublet, and for £14.49, how could I resist?

Retailers refer to this one as a "Balmoral" doublet and it is most famously worn by the Duke of Rothesay. Highland Clans says it is usually worn buttoned up with a black bowtie and waistplate belt worn over it (photos below). They say this look would be suitable for either black or white tie formal. They also suggest that this doublet could be worn open for a less formal look but there are no examples...

OC Richard has posted pictures of older-style jackets that resemble this one, but apart from that, the only recent photos I have seen are of Prince Charles. The Duke of Rothesay is, of course, a good example to follow, but does anyone else have pics that could help guide me?

I'm wondering a few things like if the belt could be left out? What other types of neck wear could work i.e. stock tie, cravat, jabot, or long tie? What about the shirt?

If I wore it open for a less formal look (as per Highland Clan's suggestion), how could that look in terms of the rest of the outfit? How much less formal are we talking here?

Here are some pics.

My new (used) doublet:


The buttons on it appear to have St. Andrew?


The image from Highland Clans:


The Duke of Rothesay:



One of OC Richard's vintage photos of a similar doublet: