Richard Osman says he felt like he was “cheating” on his beloved Thursday Murder Club characters when writing his new standalone thriller.

The four novels in his series featuring former spy Elizabeth, ex-union activist Ron, former nurse Joyce and retired psychiatrist Ibrahim, who meet weekly to solve cold cases at a luxury retirement village in Kent, have all been global bestsellers.

They are being brought to life in a Netflix film produced by Steven Spielberg and directed by Christopher Columbus, which started shooting last month.

But Osman, a guest at the recent Theakston Old Peculier Crime Writing Festival in Harrogate, put his book series on hold for a year to write We Solve Murders, which features a father and daughter detective duo and is set for release in September.

The Pointless creator, 53, told the festival – which is supported by the Sunday Express – that writing the book “felt like I was cheating on my other characters, it felt like I was having an affair”.

He added: “I made peace with myself in thinking the Thursday Murder Club characters are still there.”

The movie sees Dame Helen Mirren as Elizabeth, Pierce Brosnan as Ron, Celia Imrie as Joyce and Sir Ben Kingsley as Ibrahim. Out next year, Osman said: “It is different to the film I would have written but it’s fantastic to see what an expert like Columbus and those actors can create.”