A new book called How to Save a Life: The Inside Story of Grey's Anatomy will have Grey's fans reaching for smelling salts with all the behind-the-scenes revelations.

A chapter which is dedicated to Patrick Dempsey aka Dr McDreamy, alleges he was not always a dreamy workmate while filming his last few seasons and this ultimately led to the untimely death of Dempsey’s character Dr Derek Shepherd in season 11.

Grey’s Anatomy employee Jeannine Renshaw said: "There was a lot of the complaining… I think Shonda [Rhimes, showrunner] finally witnessed it herself, and that was the final straw. Shonda had to say to the network, 'If he doesn’t go, I go.' Nobody wanted him to leave, because he was the show. Him and Ellen. Patrick is a sweetheart. It messes you up, this business."

Speaking about season 11 Dempsey said: " That] was the first year that I haven’t been in every episode. I [was] in every episode since the pilot— close to 250 episodes. That [was a] huge run."

Speaking about the decision to kill off his character Dempsey said: "I don’t remember the date [I got the news]. It was not in the fall. Maybe February or March.

"It was just a natural progression. And the way everything was unfolding in a very organic way, it was like, 'Okay! This is obviously the right time.’

"Things happened very quickly. We were like, 'Oh, this is where it’s going to go.'

Recalling his last day Dempsey said: "It was like any other day. It was just another workday. There was still too much going on. You're in the midst of it - you’re not really processing it.

"I very quietly left. It was beautiful. It was raining, which was really touching. I got in my Panamera, got in rush-hour traffic, and two hours later I was home.

"Lots of people [miss him]. 'It’s good to see you alive' is the comment I get. I’m like, 'Yes, I’m very much alive in reruns.'

"People were really invested in that relationship. I knew it would be heavy. Very happy to have moved on with a different chapter in my life."

Rhimes said: "Derek Shepherd is and will always be an incredibly important character—for Meredith, for me, and for the fans.

"I absolutely never imagined saying goodbye to our McDreamy.

"Patrick Dempsey’s performance shaped Derek in a way that I know we both hope became a meaningful example— happy, sad, romantic, painful, and always true—of what young women should demand from modern love. His loss will be felt by all." Rhimes added.