The English know it should be called a waistcoat and have for centuries used this garment to tie outfits together.
I’m fairly certain there is a handsome dress shirt in your chest of drawers or walk in that’s been forgotten. Perhaps even a sport coat? You forgot them because these items don’t seem to equate to much alone, but when tied together with a tweed waistcoat could, perhaps, soar to great heights, the whole greater than the sum of its parts.
The English way.
The Tweed Waistcoat (No. 5179). Single-breasted. Wool blend tweed. V-neckline. Back of waistcoat as well as front lining is dark brown taffeta. Welt pockets at waist on each side (for your pocket watch). Adjustable self-fabric back belt with metal buckle.