Like English Bloke I have seen the Charcoal Tweed PC adverts on ebay, along with variuos other colors available in Barathea--typically forest green, navy blue, and burgundy.

I am not a particular fan of the look of the grey Charcoal PC as shown on the ebay ads. Also not being that deep into the Scottish heritage regardsing socially acceptable expectations in this regard I can only say that I think if done well with the right material it could pass muster, similar to some of the tartan jackets and waistcoats that I have seen on threads here under dress apparel.

Just one man's (relatively ignorant) opinion.