With another Inspector Morse spin off set to air early next year, author Colin Dexter is being kept busy with the scripts for the latest adventures of his Wagner-loving, classic car-driving detective. Chris Price caught up with him.

Sitting comfortably at his Oxford home, author Colin Dexter never forgets his manners when asked how he is.

“I’m struggling a bit but are you all right? I will do my best to answer you with honesty and goodwill.”

Remarkably agreeable for a man who has killed more than 80 people, albeit in his 14 Inspector Morse novels and the TV series. The show, starring the late John Thaw, ran from 1987 to 2000 and has spawned two spin-offs still in production at ITV. Lewis has just finished its sixth series and filming is underway for a series of Endeavour, the prequel to the Inspector Morse programmes, set for broadcast early next year.

Colin still reads the scripts of every Lewis and Endeavour and is often found on set during filming. He has made cameo appearances in almost all Inspector Morse and Lewis episodes, something he is casual about. “They wanted me to go along because they said it gives them confidence,” said Colin, 82. “They have been kind to me. The good lady in charge of Lewis and Endeavour was with me this week and spent a day going through the scripts, which come in regularly.

“It is the only positive contribution I have these days. I get treated wonderfully well. Not many crime writers can say that.” Crossword-loving, ale-drinking Colin speaks slowly and deliberately but often using elaborate words. His voice always carries a warm tone, which will instantly endear him to the audience at his Q&A show at Tonbridge School’s EM Forster Theatre.

“I’ll talk about the usual,” he said. “Most people want to hear about TV, of course but it depends on what they want and how many turn up. Where am I going anyway?”

Bizarrely, this does not sound flippant. His question carries the charm only exuded by well-meaning old men.

“I do fewer and fewer really because I’m now in my early 80s and I have got a season ticket to every medical department within 20 miles of Oxford,” he joked. “They look after me but I have had a difficult three or four years.”

Colin is losing his sight – mainly due to old age – and has been blighted by deafness all his life. It forced him to quit the job he is most proud of in his career, as a teacher, in 1966. Mobility has also become an issue.

“I struggle along and I can still talk all right if I can think about what I am going to say. There are so many things people want to know and they want to be amused. They don’t want to know about the internal political situation in China and I have never spoken about that anyway. Will I be talking to boys or masters?”

It’s explained he will be talking to the general public. He is taken aback.

“I do make people laugh occasionally but I have never said anything of any real significance,” he said, preemptively apologising to his crowd. “I usually look forward to the shows though and enjoy it very much.”

The conversation is dotted with lots of tangential episodes, often coming back to his work as a teacher, for which his affection becomes ever increasingly apparent.

Before he began crime writing, Colin had already written three textbooks during his days as a teacher. They were released by the later disgraced media tycoon Robert Maxwell, then boss of an academic publisher.

“I knew that I could write,” said Colin, who famously began work on his first Morse novel at the kitchen table on a rain-sodden family holiday in Wales in 1973.

“I was not sure that it would be of any interest to anybody. I had some experience and that got me into the habit of occasionally writing a paragraph or two.

“But the best thing I ever did was teach Latin and Greek. I look back on that with the greatest pleasure.”

He joked: “That is where I went wrong. Deafness has blighted my life. If I had not been deaf, I would have certainly stayed in school teaching all my life.”

Colin comes across as something of a reluctant success. There are similarities between him and his famous fictional detective, who he based on his friend, the former chairman of Lloyds Bank, Jeremy Morse.

“Inspector Morse has an inability to resist a drink and always tried to give up smoking,” he said. “He never did any exercise and many people have been through those stages. He is very much on the audience’s level.”

As the interview ends, that is how it feels with Colin. A man on your level.

An Audience with Colin Dexter is at Tonbridge School’s EM Forster Theatre on Thursday, September 13. Tickets £15, concessions £12. Box office 01732 304241.