Miskatonic University PressFurther to the Yellow Car in London Rules, there’s a Yellow Car in the next book in Mick Herron’s Slough House series, Joe Country (2019).
Traffic shunted forwards, and came to a halt again. The lane heading back to London was moving freely, if with wariness; the snow was drawing black lines on the road where tyres had cut through it. It occurred to River that the lanes up ahead, the far side of the spilled load, might be inches thick by now. But we’ll plough that furrow when we come to it.
“Yellow car,” said Shirley.
“What?”
But she didn’t explain.
And the snow kept falling.