Vintage bespoke (most probably Frank Hall) 
Blue and black tattersall check frock style wool waistcoat
 
5 horn buttons
2 outer breast slit pockets
2 outer flap waist pockets
frock style 
Blue/ black wool Tattersall lining
Cream wool back
Adjustable back
 
This is just gorgeous and in my opinion probably a vintage Frank Hall Tailors of Market Harborough waistcoat
 
All measurements taken on the outside with the garment laid flat:
 
Across chest 20'
Nape to hem at back 23'
Nape to bottom of points 25.5'