Think Call The Midwife is all vintage costumes, chubby-cheeked babies and jolly post-wartime sing-alongs? Think again. Ever since the first episode aired in 2012, the writers have made a point of featuring dark and deeply upsetting storylines – including the thalidomide scandal of the 1960s, female genital mutilation, domestic violence, rape, illegal abortions, contraception and homophobia.

So why do people still assume, all these years later, that the show is the perfect accompaniment to a cuppa and a slice of cake? The show’s creator, Heidi Thomas, has a theory.

Speaking to the Radio Times, Thomas says: “I’ve been in a state of mild rage for about seven years now. Because Call the Midwife – certainly in its early days – was often dismissed as being lightweight, fluffy.

“It was called TV Horlicks because it was about women.”

Thankfully, though, many have woken up to the fact that Call the Midwife doesn’t just pay lip-service to hard-hitting issues – it teaches us valuable lessons about them, too. 

And perhaps the best example of this is the show’s incredibly sensitive handling of Nurse Trixie Franklin’s alcohol addiction.

When we first met Trixie (Helen George) in 2012, we assumed we knew everything there was to know about her from the get-go: she was the fun, glamorous and vivacious nurse – always bubbly, always ‘up’, and always oozing confidence. Her make-up was pristine, her hair perfectly coiffed, her wardrobe enviable. Her convent bedroom was filled with magazines, lipsticks and hair curlers. Her fashion advice was always on-point – as was her straight-talking stance on matters of the heart.

And, of course, we were fond of her unabashed approach to all things naughty and decadent: Trixie was the one, after all, who could always get her hands on a sneaky Babysham, or whip up a creative cocktail from the remnants of the liqueur bottles stashed in her wardrobe. She was the one who’d encourage the girls to grab their toothbrush mugs and pour them a generous slosh of G&T during their evening chats. She was the one who, at a party, wouldn’t say no to one or two glasses of wine.

The young nurse’s alcohol consumption was presented, at first, in a positive light. Over time, though, this began to change: we’d watch her stay up all night drinking with her friends, or regularly pour herself a large glass (or two) of her favourite tipple to help her unwind after work. By season four, the rug was pulled almost entirely out from under us when she began visibly using alcohol as a crutch – and she passed out one night, drunk, after calling off her engagement to Chaplain Tom Hereward.

Eventually, Trixie was forced to face up to the truth: she was an alcoholic. With the support of Sister Mary Cynthia, she joined an alcoholic support group and, since then, she’s come along in leaps and bounds. She’s as bubbly and confident as she ever was – and she’s (seemingly) committed herself to a life of sobriety. Naturally, we assumed this was one of those storylines that had been neatly tied up with a bow: Trixie’s alcoholism was cured.

Unfortunately, though, life doesn’t work like this. In fact, the hard evidence is that alcoholism is a lifelong condition. Why? Because although you read about the odd person “never” experiencing cravings again, thousands of people in virtually identical positions do not experience the same cure. Because you still spend a lot of your time thinking about drinking, or rather not drinking. Because drink’s always on your mind and at the forefront of your thoughts – and Call the Midwife writers are all too aware of this. 

So it makes sense that, in the current series, they decided to revisit the storyline.

After a run of professional challengers and a personal setback, worried viewers watched as Trixie relapsed into dangerous old habits. She swigged vodka in the bathroom, where nobody could see her. She drank sherry with patients. And, most worryingly of all, she skipped her support meetings.

“She’s not in a good place,” says George of her character.

After eventually finding the strength to open up to Sister Julienne about her ongoing struggle with alcoholism, Trixie made the difficult decision to leave Nonnatus House for six months to get treatment.

She will appear briefly at the start of next week’s installment before leaving the show for several episodes (as part of George’s maternity leave contract).

And, while an undeniably upsetting storyline, the show has been praised by viewers for its realistic portrayal of alcohol dependency – and for inviting us to question our assumptions about what someone with an alcohol addiction ‘looks like’.

Many of us, upon hearing the word ‘alcoholic’, will imagine someone dishevelled and distressed; a person whose life is falling apart as a result of their addiction. Trixie – youthful, beautiful and chic – doesn’t fit the mould. Yet her creators are clear: she has a problem, and she isn’t the only one.

Frequent alcohol consumption which apparently has no adverse effects on a person’s day-to-day professional or personal life is a significant national problem. In 2007, the most recent year for which statistics are available, 33% of men and 16% of women were classed as hazardous drinkers by the NHS, and a high proportion of these were likely to be high-functioning alcoholics.

To diagnose a functioning alcoholic, experts use the four letters in the acronym CAGE.

C – Cutting down 

Do you ever think you should probably drink less?

A – Annoyance 

Do you ever feel annoyed by people complaining to you about your drinking?

G – Guilt 

Do you ever have feelings of guilt about your drinking or what you do when you drink?

E – Eye-opener 

Do you ever feel like you need a drink to feel better, particularly in the morning to unwind?

You don’t need to answer yes to all four of the questions to identify as a functioning alcoholic. In fact, if one or two are answered positively, it’s highly suggestive you could have a problem with alcohol

Dr Iqbal Mohiuddin, a consultant psychiatrist at 25 Harley Street Day Clinic, estimates that a massive third to a half of the people he sees for alcohol addiction don’t prescribe to our stereotypical image of an alcoholic.

“They’re working in high-powered jobs, in the City or the media and drinking heavily is accepted, almost expected,” he said.

“They have carried on for years in this way but suddenly they’re getting physical symptoms such as feeling sick in the mornings and needing a drink and perhaps a partner has said they have had enough and it’s the drink or them.”

To help lower your risk of “alcohol-related harm”, the NHS has published a number of recommended guidelines online.

These include:

• not regularly drinking more than 14 units of alcohol a week

• if you drink as much as 14 units a week, it’s best to spread this evenly over three or more days

• if you’re trying to reduce the amount of alcohol you drink, it’s a good idea to have several alcohol-free days each week

The guidelines add, “Regular or frequent drinking means drinking alcohol most weeks. The risk to your health is increased by drinking any amount of alcohol on a regular basis”.

You can calculate how many units of alcohol are in a variety of different drinks using the Drink Aware unit calculator here.

If you think you or someone you know might be suffering from alcohol addiction, you can find support here.

Call the Midwife airs at 8pm on Sundays on BBC1

Images: BBC One