An almost-black grey.
"I'm in the process of finalizing a mantel design for the gas fireplace at our country house," explains senior design editor Margot Austin. "I want to make the fireplace look as much like a wood burning one as possible. I will do this by using a paintable faux-brick surround and a simple mantel, and then paint both in a deep charcoal grey to match the fireplace box frame, like Farrow & Ball's Railings. I think by minimizing contrast you will see the mantel shape first and not the gas insert. Then I'll light a Diptyque Feu de Bois candle and the the illusion will be complete!"
Browse more of our Editors' Favourite Winter Paint Colours in our photo gallery.