Odd waistcoat with black barathea Argyll?

[Steve Ashton]

The top jacket in my photo is a standard Black Barathea Argyle style with square buttons.
Note please that the buttons on the red vest are round horn.

The second photo is of a Tweed Kilt Kut suit coat. This jacket is a three button front, de-militarized version, much more like a regular suit coat.
The charcoal gray jacket and dove gray vest have the same buttons.

In the period up to WWI a man may own only one suit coat. But he may have many vests and would change up his outfit by wearing a different vest.
In general, Tweed was considered a less formal type of attire suitable for outdoors or the country. More formal occasions would usually mean a solid color with darker being more formal that lighter.

So, if I am attending an outdoor event or one of the jacket and tie level of formality you will usually see me in the Charcoal Tweed KKSC. Usually with contrasting vest.
For a slightly more formal setting, say a funeral or business attire where the men wear 3 piece suits, I may wear a matching vest.
After 6 pm or for a tad more formal event with a Scottish theme I may wear an Argyle. I would not usually wear an Argyle style jacket outside of a Scottish themed event, but if I did, I would view a contrasting vest less formal than a matching vest.

The idea is to match what you wear with the level of formality of the event you are attending. I have seen Prince Charlie jackets worn at Highland Games and it just looks odd. But an Argyle style jacket with matching matching vest at a Burn's dinner is quite common.

About 99% of the time I am not at a Scottish themed event. I am just the guy who wears a kilt everyday. So on most occasions, where a jacket and tie are appropriate, I wear a contrasting vest. I just like the look and it is not the 'cookie cutter' look that you see so often sold in shops where there are kilts.