On the day I saw this comedy about cancer, the death was announced of the journalist Steve Hewlett, whose treatment for the disease had been closely followed by Radio 4’s PM programme.

As always with this kind of death, the news was both expected and a shock. Over the series of interviews conducted by PM presenter Eddie Mair, Hewlett’s smooth, even voice became more gravelly and fragile until our and his hope that he might be saved, or at least his death delayed, by ground-breaking treatment was overcome by the sheer aggression of his cancer.

The interviews made for riveting listening, despite Mair’s habitually laboured attempts at humour.

Mair’s mannered irreverence usually comes across as a well meant but ill-judged attempt at providing a little light relief from the serious business of news.

But when the presenter indulged in one-way joshing with Hewlett about the latter’s wedding plans, a further weight was added to Mair’s already leaden attempts to raise a smile.

As if anyone needed reminding, it became clear just how difficult it is to get the tone right when talking about terminal illness.

Admittedly it is a challenge that is even harder for mirth-challenged Mair than it is for most, but imagine how much harder it must be for a musical to deal with cancer, and harder still for a musical that wants to make its audience laugh.

And yet, among all the things that could have gone so very wrong with Gary Barlow and Tim Firth’s new show, and instead went so very right, most impressive was the tone.

Misjudge a joke and you risk being trite. Over-emphasise grief and you blunder into the maudlin. Death is a minefield. But, with amazing sure-footedness, this show finds the laughs and elicits the tears in exactly the right amounts at exactly the right times.

That said, Firth has become an expert teller of one of stage and screen’s most enduring stories. He wrote both the 2003 film and the play versions of Calendar Girls on which this show is based.

You’d think he’d had enough. You’d think that anyone who had seen the film and the play had had enough.

But new life has been breathed into this real life-inspired story about a group of respectable Yorkshire WI ladies who stripped for a calendar and good cause after the husband of one of them dies of cancer.

It was hoped the proceeds would pay for a new sofa in the hospital where he was treated. So far the ladies — some of whom came up on stage at the end of the performance — have raised over £5 million for leukaemia research and they are still counting.

Joanna Riding as the wife of Yorkshire Dales park ranger and cancer victim John (James Gaddas) embodies the balancing act of this show. From the tender and soaringly stoic score, only the impromptu Christmas song Who Wants A Silent Night? felt oddly laboured in its attempt to reveal the passions that lay within these outwardly conservative women. But the song in which Riding’s Annie asks who is going to help open the stiff back door after the ailing John has gone is a beautifully observed list of the mundane things that it takes two to do.

And if that sentimentality needed an antidote it is delivered with anger at the injustice of seeing a good man die while bad people live, a sentiment that anyone who has lost a loved one to cancer will recognise.

But it’s probably Debbie Chazan as neglected wife Ruth who best embodies the tragi-comic heart of the show. Initially appalled at the thought of taking her clothes off no matter what the cause, and further humiliated by her husband’s betrayals, she works up Dutch courage in the form of her “Russian friend”, a bottle of vodka, later bursting into the photo shoot in a glorious display of comedy drunk acting as she draped her body around a fruit display.

It’s in this scene that something rather wonderful happens — when ladies of a certain age, but every size, shape and character, pose for pictures.

There is a daring amount of buttock and boob exposed but, as Barlow and Frith’s signature tune called Dare says, you should never do what age expects of you, which is as life-affirming a message as you could wish for.

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