Sir Paul McCartney always chopped onions when cooking with his late wife Linda McCartney because he wanted to spare her the tears

Reminiscing about his kitchen exploits with his first spouse, the 'Glass Onion' rocker said: "I would always volunteer, because we were very close and I was often in the kitchen by her side. I would say, 'Anything you'd like me to do?' And one thing I didn't mind doing was chopping the onions - even though it made me very emotional ... I'd even cry sometimes!

"I quite liked chopping the onions, I liked the idea of sparing Linda the tears.

"Generally speaking, I wasn't a bad cook. But she was so much better that I only did the occasional meal. I did a good breakfast - I would use a lot of fruit, peel the mango and cut it all up, slice the melon and deseed it, and make it all nice on the plate.

"But she was definitely the main cook: the 'Cook of the House'."

Paul and Linda became vegetarians in 1975 and she went on to launch the Linda McCartney Foods range, which specialises in vegetarian and vegan items and is still popular now.

The 'Let It Be' singer - who launched the Meat Free Monday campaign back in 2009 to encourage people to ditch animal products from their plates once a week - is proud to have been a pioneer of vegetarianism which has been adopted by millions around the world.

He said: "It was a joint decision, definitely. We were both quite happy eating meat, because she was a great cook, and we didn't really think about it until we were on the farm one day eating a lamb dinner and both realised that the lambs outside were what we were eating. We didn't like that.

"We said, 'Shall we try going vegetarian?' And actually, it was a very exciting point in our lives, trying to think of what we would have to fill the hole in the middle of the plate.

"Now of course, it's really not difficult at all. You just go down the shops and most places will have great veggie options. It was a joint decision and we never looked back. It was a great thing to do, and it turned out we became part of a vegetarian revolution."

Paul, 79, and his daughters Mary and Stella have created a new cookbook featuring updated versions of Linda's plant-based recipes and numerous meals the McCartneys eat at home.

'Linda McCartney’s Family Kitchen', by Linda, Paul, Mary and Stella, is available now.