Thanks guys (especially for the photos). I was erring on the side of a dark charcoal grey jacket and waistcoat (good point about nothing shiny) but was put off by the Argyle sleeves and brown horn buttons on some. I've seen a Tweed Crail jacket which looks interesting or, of course, I could go for a charcoal Argyle and accept the sleeves but change the buttons... choices, choices!

All the best
Graham.