According to [Linda McCartney's] confidante Peter Cox ~
Mr Cox is the man in possession of the 'Linda Tapes' - 20 hours of conversations recorded when he was writing a cook book with her -
The Jane Asher effect
Mr Cox said that on days when Linda was feeling uninspired, he would use his 'secret weapon' - a cake recipe book by Jane Asher, Sir Paul's former fiancée.
"If she was a bit down, I'd slam it on the kitchen table and it acted like a red rag to a bull. Linda would say: 'Right, let's get going'."