“All us tough guys are just hopeless sentimentalists at heart," Raymond Chandler once wrote in a letter that described how, on the anniversary of his wife's death, he'd filled his house with red roses and sat around drinking whiskey. Chandler was so broken-hearted about her death that he even attempted suicide - so how much of a tough guy was he?

In A Coat, a Hat and a Gun (3 February, 11.30am), timed to coincide with the start of a season of plays based on Chandler's work, Harriett Gilbert visited the mean streets of the tough guy's alma mater Dulwich College, in south-east London. The lingering traces of the public school boy's uprightness and code of honour in Chandler's Los Angeles are what make his work both so elegiac and occasionally a bit ridiculous compared to that of James M Cain or John D MacDonald.

I love Harriett Gilbert - she and Mark Coles are the best presenters on BBC Radio. She never puts herself forward, never dominates her programmes in the way that arts presenters such as Bidisha tend to do at their worst: she is modest, relaxed and intelligent. You hardly ever notice her (in the best way). And it is worth noting, amid the brouhaha about ageism in the BBC, that she is in her sixties.

When she mentioned that, as a little girl, she had once answered the phone to Chandler, who was calling her writer father, and she had been wearing her "ladybird shorts", it was the first time that I had ever heard her say anything about herself.

In Dulwich, a librarian rustled up an old photo of Chandler as a schoolboy. "He looks distant," the librarian said. "He looks miserable," said Harriett. This was the defining aspect of Chandler's life: he was always haunted by failure and was rarely happy. Only late in life - pushing 50 - did he come to the satisfactions of literary achievement. The Marlowe books depend on the tension between ugly self-pity and bitter-sweet sadness. Chandler could be very funny, but his best paragraphs are beautiful little poems of sorrow.

Harriett had rounded up a deftly chosen cast of the usual suspects - John Sutherland, David Thomson, and so on - and one of them pointed out that Chandler's primary literary interest was neither plot nor character but cadence. It was all about the voice for Chandler, which makes him - or ought to make him - ideally suited to radio adaptation. But does it?

As anyone who has seen Michael Winner's 1978, worse-than-Maybe Baby, all-time cinematic nadir version of The Big Sleep will know, the story, in dramatic terms, is not very solid. The best way to adapt it would be as an audiobook. The 90-minute running time of this radio version (5 February, 2.30pm) was a squeeze. The climax of the novel is Marlowe's wounded rejoinder to Vivien Sternwood (Lauren Bacall in Howard Hawks's 1946 film version; Sarah Miles in Winner's - perhaps the worst screen performance ever given), who thinks that he means to blackmail her. It is one of Chandler's great, semi-misogynistic riffs of Marlovian integrity. And it's the point of the whole book! Definitely uncuttable. But it was gone - a victim of the format.

However, Farewell My Lovely (19 February, 2.30pm) and The Long Goodbye, which will be broadcast later in the year, are structurally more satisfying. It will be worth tuning in to hear more from that hopeless sentimentalist, the bluesman of Dulwich. l