This is a play on The Little Red Book - a list of quotes from Chairman Mao, the Chinese Dictator.
Mr McDonnell famously quoted the book in the chamber.
4) The final joke came at the cost of another Tory MP.
Mr Sunak, announcing continued tax relief for the red diesel used in tractors, poked fun at his colleague Mark Spencer - a former farmer.
"I've heard the concerns about agriculture, particularly from the [National Farmers' Union], rural colleagues and indeed my Right Honourable friend, the member for Sherwood."