We call ourselves ivy over here. It's the same as trad but we have a long running feud with them so we have to pretend to be different. (Even though about half of us go on here and the trad forum).

Ivy specifications for ties are a lot less specific than they are for other items - if everything else is kosher ivy then any decent subtle colour/patterned tie will work. Post photos of particular Hermes ties and we can comment. The only Hermes I recall having seen were pretty nasty but I may be mistaken.

The real name is actually natural shoulder clothing.

Guys, don't be dumb. It's TNSIL.

I am talking about the traditional abstract patterns

I'd need to see an example.  Abstract sounds too arty or modern, but I could be wrong.

https://a.1stdibscdn.com/archivesE/jewelry/upload/245/855/XXX_245_1357418845_1_1.jpg

Not ivy but Euro business trad, I could also see them on early 1990ies Fraisier types

I would see vintage Hermes as American Business Man New (post 1980) Tradvy

People are aware of the brand name even if they do not recognise their products.

Charvet are an altogether nicer French tie.

Ivy types are pretty buttoned down though. So -knit ties excepted - it is the sort of ties that were part of your school uniform or strictly geometric patterns. They never get bored with it.

Fred flinstone may well be part of the Ivy "go to hell" look along with trahseez featuring small animals. They dont tend to do gundog ties though to their credit. Unless they graduate to the "Ask Andy" Barbour  brigade who dont realise that people are laughing at them.

Not so much forbidden, more a case of lacking the confidence to try something like a Liberty tie.