I would recommend The Manual of Linotype Typography, published in 1923, but it doesn't list a Didot ornament series of ornaments. The closest it comes is a Bodoni series.

Akira Kobayashi's FF Acanthus has some good neoclassical ornamentation.

But surely the point of the Didone (modern) style was a spartan classicism.
The only ornament really necessary when working in this style is the bulging rule; IIRC H&FJ have a few of those.

Various Didone glyphs have been used decoratively, such as the asterisk.

I included a few dingbats (not really ornaments) in Scotch Modern.

It's made me wonder why the ornament cuts were developed in the first place, was this a 'fad of the times' or something that was added at a later date? I really know very little history of ornaments.

There seems a lot of attention in getting them to mirror a Didone ascetic of unornamented structure and a "modern" appearance, I would have thought ornaments useful in typographic design of today when you see attributes of fonts like flourishes becoming (perhaps too) popular within typography also.

It's made me wonder why the ornament cuts were developed in the first place, was this a 'fad of the times' or something that was added at a later date? I really know very little history of ornaments.

After looking at the Linotype Didot Ornaments at fonts.com, I'm wondering why they were developed, too. They are absolutely wretched...

I think Adrian Fruitger was influenced by La Henriade when he 'revised' Didot to a family of 12 weights including the ornaments in 1991, so recent editions they are.
I've heard typographers call them elegant, classic and even powerful but never wretched!
Just out of interest as I enjoy hearing constructive criticism, why do you feel that way?

...one mans rubbish is anothers treasure i suppose :)

It would appears that whoever designed the Didot Ornaments shown above took "Modern" to mean "Art Moderne," a.k.a. Art Deco,a style which they attempt--at least to my eye, rather poorly--to emulate.
On the other hand, the Bodoni ornaments below which appear in the book I referenced are in keeping with their actual historical period, and are--again, to my eye--rather elegant.

As something of an historical purist, I would have to agree with Nick.

However, as this is design, the purpose of which is to resolve contradictions, there may be a way to make good the ornaments with their typeface. The harder the challenge, the more potential. Are you up for it, Hugo?

I fear I am walking blindly into an area I know very little about but that's not going to peturb me. I'll need to work with them for a while before I'll feel comfortable presenting further and I have some time (until the new year) to guideline usage of these cuts within their corporate visual guides. I'm still not sure if they will end up in there or not, I need to look at application carefully, in the wrong hands it could end up a disaster.

I'm rather excited about the reference of 'Art Moderne' by Nick though, I hadn't thought to research in that era or art style. I sense it's not an area of passion for you both but again, could you recommend further reading in this area?

I have also taken advice and purchased myself a copy of Giambattista Bodoni - Manuale Tipografico (well it is my birthday today and amazon twists the arm so well). It's one of only a handful of serious historical reference books I've bought since my college days and almost since I owned my first computer, which I'm sure is more to-do the reason. So I look forward to receiving it, it's a good read at over 1200 pages too.

Re: Art Moderne/Art Deco...

Stephen Heller and Louise Fili have a series of books on the subject. This link references many of them. I have them all and can recommend them highly.

http://www.amazon.com/Deco-Type-Stylish-Alphabets-Design/dp/0811811352