I ragged the walls with smears of Chalk Paint® in Country Grey and Paris Grey. Spritzed with a water bottle and then ragged the mixture across the wall doing two foot sections at a time. You hardly use any paint doing this technique and it gives such an atmosphere~and it's fun!
Get this look by doing a base coat in a light color. Roll a darker colour overtop - while the paint is still wet, use a dry brush to brush off and smooth the paint out - exposing the colour underneath.