In a new interview, the writer revealed that it was Shaun's idea for Inspector Morse to develop a problem with alcohol.
WATCH: Are you looking forward to season nine?
"The drinking in this season was something Shaun very much wanted to do," he told Salon.com. "What I didn't want to do, I didn't want to do a heroic drunk. Because that I find a bit dishonest."
Fans of the original 1987 series, Inspector Morse, will remember that the iconic detective frequently enjoyed drinking pints of real ale. Chatting about how Shaun's portrayal perhaps changes the way the audience looks at the drinking habits of the original Morse (played by John Thaw), Russell said: "Well, it was as much about addressing a request from Shaun that we go down that road. But you've also got to find a way of leaving him intact by the time we finish what we're doing, which is a functioning alcoholic.
"We've had Max (played by James Bradshaw) talk about it in the past, I think, Dr. Debryn? "Such-and-such character liked a drink," you know. That's the euphemism for a kind of alcoholism, or borderline alcoholism or functioning alcoholism. So that's where we've got to leave him."
It was Shaun's idea for Morse to develop a drinking problem
The new interview comes just months after ITV announced that the ninth series of the show will be the last.
Speaking about the decision, executive producer Damien Timmer said on behalf of producers at Mammoth Screen: "Endeavour has been a real labour of love for all of us, and we salute Russell Lewis for his extraordinary achievement in chronicling Endeavour Morse's coming of age across 72 hours of TV."
The show will end with its ninth season
"Russell always knew where he wanted the series to end, and that Remorseful Day is nearly upon us! We'd like to thank Shaun and Roger and all the other members of the Endeavour family on and off screen, and to the show's fans both in the U.K. and abroad."
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