His other two suits are more city than country, so this one gets a Tattersall waistcoat.
"Tattersall" isn't it funny how you take the names of things for granted- until you want to write something vaguely intelligent and then you have to look it up!
So Tattersalls has been the main British auctioneers of race horses for the last 250 years. That explains the connection of these waistcoats to wear when riding and thence the connection to country or sporting wear. It seems that there is a Tattersall check fabric - yellow with black check, which is not what I am using here, but I will call it a Tattersall for the style even though it seems that modern Tattersalls have lost most of the styling details and are now just a yellow checked vest.
My reference for this waistcoat is a tailor's sample book from the 1930's, and the details are a waist seam with two pinch pleats towards the chest, flapped lower pockets in the waist seam as well as two chest welt pockets. Some references show a collar. This one does not have a collar nor the pinch pleats although in the past I have made them with both.
In the photo above, you can see the waistcoat fronts with the pocket parts, the canvas support for the front and then the facing and front lining.
Now that I see it here, I think I will cut a waist seam in the facing, because I want a buttonhole right on the waist seam. I want it to be created by leaving a space unstitched in both the fronts and the facing. When the seam allowances are pressed open on both parts, all I will have to do is cut the canvas and then either just whip the fabric edges together or sew a buttonhole stitch over the opening. This is often a neater finish than a machine buttonhole through all the layers of seam allowance.