The recent winter coats thread has reminded me that my much loved wool and cashmere work coat from a top end diffusion line, which I spent an arm and a leg on in a 20th century January sale is reaching the end of its life. 
I have other tailored wool coats for work, which are fine for November, December, March, but they’re a bit lightweight and have nylon/polyester in with the wool. For the times when it’s properly cold I want a seriously warm coat that will stop me from freezing to death in the forced march through the winds whistling over London Bridge but still look really smart over a work suit.
Can anyone suggest brands that might fit the bill without costing four figures? Or is this one of those things where the only answer would be to spend terrifying sums of money and I just have to live with my increasingly threadbare old darling?