I have a green three-button waistcoat that I used to wear with a PC until, quite unaccountably, it appears to have got smaller. I also have a red one that fits. This really stands out in a crowd! Cream (putty) also works well. IMHO a good contrast is always better than a bad match. Dark jackets often look good with light-coloured waistcoats and light jacket with dark waistcoats.
Bookmarks