Sarah Lancashire is firing off jokes as if they’re going out of fashion. She laughs that when she saw Maggie Smith’s brilliant performance in Gosford Park, "it made me want to become a plumber". Her lack of a glamorous wardrobe sends her into fits of giggles; gesturing to the casual outfit she is wearing for our meeting - a floaty, knee-length floral halter-top, white trousers and white plimsolls - she explains: "This is my idea of dressing up. It just means I’ve ironed my clothes."
There are no two ways about it: Lancashire is on sparkling form this morning. She has the aura of someone who has both her private and professional lives sorted. As well as being the wife of Peter Salmon, the BBC’s head of sport, and the mother of three boys, 16-year-old Thomas, 13-year-old Michael (both by her first husband, the composer Gary Hargreaves) and 14-month-old Joseph (by Salmon), Lancashire is also one of our hottest TV actresses, a performer so much in demand that two years ago she could choose not to renew a 1.2million ‘golden handcuffs’ deal with ITV.
She returns to the channel early next month with another star vehicle, Rose and Maloney, in which she and Phil Davis play a pair of crusading investigators for the Criminal Justice Review Agency, seeking to overturn miscarriages of justice.
Letting her blonde hair fall loose over her shoulders and unashamedly puffing on a cigarette - "I’m not planning on being a health role model" - Lancashire has an easy-going allure about her. For someone who has in the past admitted to extreme anxiety in company, she is admirably relaxed now.
As we chat over tea and biscuits in a central London hotel, Lancashire exudes charisma. It is precisely that quality which leaps out of the screen, endearing her to viewers. Stephen Whittaker, who directed her in ITV1’s Sons and Lovers, reckons that if she chose to, she could become a Hollywood star. "She’s not conventionally beautiful," he says, "but she has a real sexiness, a frontierswoman quality, adaptable to all sorts of roles. She is a real leading lady."
Hollywood, however, is the last thing on Lancashire’s mind. She is quite content in Twickenham, south-west London. "I am very happy with my life now," she says. "Everything is under control, nothing is running away from me and it has all turned out just how I hoped.
"I feel that my life really begins from this point forward. Now I have my whole life ahead of me and I want every single, lovely moment of it. Before, my life was a bit of a labour, to be honest with you, but now it feels pretty damn wonderful."
The "labour" Lancashire is referring to is her struggle with depression. During the mid-1990s, she had a breakdown while playing the bubbly barmaid Raquel in Coronation Street.
The actress recalls grim times suffering from what Winston Churchill called his "black dog’’; she was on medication and twice contemplated suicide. "In my early days, depression did inhibit me because I was too debilitated and terrified to tell anyone why I couldn’t get on a train from Manchester for auditions in London," she says. "I fully believed I’d lose work if I admitted to it. Tranquillisers were the worst thing for it and I ended up in a terrible mess. My twenties were a write-off."
Concealing the condition only made it worse. "Things get blown out of proportion when you’re trying to hide something you feel guilty about," Lancashire continues. "It’s a cruel illness, because you can’t see it and you can hide it so well. At least, I can. I’m a genius at hiding it. I think a lot of people are. Actors are bloody marvellous at hiding."
Lancashire sighs at the memories. "My family knew, but I didn’t tell anyone at Coronation Street and I didn’t take any time off. I just battled along, which was the worst thing I could have done. Every day I was hysterical at the thought of getting out of bed, but I made myself do it.
"When you pretend for a living and you have to pretend in your private life as well, it’s very sad. Because it’s intangible, depression is an issue that people don’t like to talk about. It’s like a huge, guilty secret."
But the actress couldn’t carry on like that. "It was a time bomb waiting to go off. It was my mother who said: ‘enough’s enough’. It must be dreadful to watch someone you love so debilitated and she literally dragged me to the doctor. It gave me my life back."
In 2000, Lancashire finally plucked up the courage to "come out" as a depressive. She now believes it is the best thing she has ever done. "When I was finally able to admit it and get it all out of the closet, I felt so liberated. I could say, ‘Yes, I’ve got the full works. Yes, I’ve been to that hospital’," she recalls. "It allowed me finally to be myself. The worst thing is the shame that goes with depression, but I really don’t feel that any more."
Lancashire hopes that her honesty about this condition will help to de-stigmatise it. "It’s incredibly common and in most cases it’s treatable," she observes. "It’s not something I’m embarrassed about. Depression is an issue that tends to be brushed under the carpet. My hope is that if people with a public profile are prepared to talk about it, then it might prompt other people to talk about it too.
"If I can encourage just one person to say ‘look, I’m one of them and actually I’m doing more than fine’, then that would be great. People need role models. I remember reading about the comedian Bill Oddie’s depression and thinking, ‘good on you’. He’s known as a chirpy man, but it shows that it can happen to anyone and shouldn’t be stigmatised."
Lancashire is an example to anybody who has ever thought: stop the world, I want to get off. "I’ve definitely made friends with my depressive self," she says. "I’d like to think that I’m a little more together."
One of the things that has helped is her three boys. Over the years, Lancashire has found that "children are buoyancy aids. When you feel like putting your head under, they pull you back again."
That feeling only increased with the arrival last year of Joseph. "Being a new mum is amazing," she says. "I am loving every minute I spend with Joseph and all my boys. It’s very difficult to disguise how I feel - I’m afraid I just can’t stop smiling. I am very happy with my life now."
The only aspect of motherhood that she does not enjoy is the sleepless nights. "I could definitely do with a decent night’s sleep. I haven’t slept for the entire 14 months."
For the rest of the time, however, Lancashire seems to be coping well with the difficulties of keeping several different balls in the air at once. "I’ve been juggling for such a long time now that it’s normal," she smiles. "When all the plates are in danger of coming crashing down - when the phone is ringing at the same time as someone needs their bottom wiped - I do occasionally look at people who don’t have children and wish that I could swap places for just 24 hours. But overall it’s a blissful form of chaos.
"It’s also a chosen form of chaos, so I’m certainly not going to complain about it. And two-thirds of women are experiencing exactly the same as you every single morning, so you know you’re not alone. The way I see it, you’re actually going to work for a rest. You can’t put a price on peace of mind - and that’s what you get at work. Only having to focus on one thing is a blissful relief."
Lancashire’s life outside acting appears to have given her more of a down-to-earth perspective about her profession. She sees acting as just a job and is certainly not caught up in the ‘look at me’ celebrity mania that seems to grip so many stars these days.
"I don’t live a famous person’s life,’’ she says, as if daring me to contradict her. "I don’t buy into that celebrity culture at all. If you dance with the devil, you’re going to get burned. I don’t see fame as being part of the job description. Some actors do very well out of the fame game, but I don’t do it because I’m absolutely hopeless at it. There’s no point. I don’t ever expect people to know who I am just because I’m on television - why should they? And when I try to look glam, I just look stupid. It’s all about self-knowledge.
"The celebrity life is there if you want to take part in it, but when I went into the Street, I already had two babies, so after work every day I had to go home and resume normal life. In the same way, during three years at drama school, no-one even mentioned the word fame. I never thought, ‘I’m going to be famous and appear on the front cover of Heat magazine’. I just wanted to lead a quiet life and that’s exactly what I do.’’
Unusually for an actress, Lancashire seems equally unfussed about her appearance and is quite happy to play less eye-catching characters. In ITV’s The Cry, for instance, she toned down her natural beauty to play a grief-stricken mother who had suffered two still births.
Lancashire says she "can understand why some actresses always want to look glamorous - if you’re known for that specific image, then maybe it’s difficult to put that to one side. But I’ve never believed my face is my fortune. I’m lucky because to me it never matters whether my face is plastered with make-up or not."
By the same token, the actress, who has three brothers (one of whom is her twin), does not seem at all bothered about her impending 40th birthday in October. "I haven’t actually thought about it, to be honest," she says. "It really doesn’t bother me. I think turning 40 is nothing nowadays - 50 is the new 40. I’ll probably just ring up my twin, wish him happy birthday like I do every year and then just get on with the day. Getting old doesn’t bother me. As long as myself and my family have got our health, that’s all that matters."
Lancashire doesn’t worry about her age affecting her career, either. "The public are not interested in lipstick on pillows any more," she says. "They want to see fine actresses in fine drama - and that may mean performers of a certain age.
"No-one should have to apologise about that. There is something lovely about older actresses. Look at Dame Judi - she’s gorgeous and a national treasure. We’ve got over the Dallas era where women had to look a certain way. We’re more grown up these days. We don’t have to think about keeping the years at bay - we’re allowed to age. The days are gone where actresses all had to be young and pretty. That was just not substantial enough."
Born in Oldham, Lancashire has drama in her blood - her father Geoffrey worked as a script-writer on Coronation Street. She went to Guildhall Drama School in London, but after graduating in 1986 she struggled at first to make ends meet and taught for five years to supplement her income from acting.
Her fortunes changed when she did a year in the London West End production of the musical Blood Brothers, before landing her big break on television in 1991 as Raquel in Coronation Street. Lancashire has since starred in such hits as Where the Heart Is, Clocking Off, Seeing Red, Sons and Lovers, Chambers and The Glass.
In the process, she has become one of a mere handful of ‘green-light actors’ in British television - those performers whose name attached to a project is enough to get it commissioned.
But for all her recent success, Lancashire has never forgotten the times when money was tight. "For years, my mother and mother-in-law would cut out money-off coupons from magazines and newspapers and I’d trot off with them.
"The woman on the till must have dreaded my arrival because I had all these vouchers that she was going to need to sort out. The great luxury of being well paid as a TV actress is not to have to take my calculator to the supermarket anymore. That means an incredible amount to me, more than you can ever imagine. I can still remember the first time it happened. I’d got my first pay cheque from Coronation Street, and I knew it was in the bank. So I knew that I could go to the supermarket and, within reason, not worry about what I bought. I shall never forget the thrill I got from doing that."
Many actors harp on about ‘staying normal’ while enjoying an absurdly pampered existence completely divorced from the way the rest of us live our lives. But Lancashire doesn’t answer that description. She does not take one iota of enjoyment from the accoutrements of the celebrity lifestyle - I think she would come out in a rash if she ever had to pose for the paparazzi on a red carpet.
She appears to derive her greatest pleasures from the simpler things in life, including gardening and DIY. "I do all my own decorating and I’ve got the hands to prove it," she smiles. Proffering her mitts for inspection, she insists, "look, I have hands like an Irish navvie."
After everything she has been through, Lancashire, more than most, knows the value of stability.
"I’m no different from any other working parent with school-age children," she concludes with a wry grin. "I still have to dash round Sainsbury’s madly on a Saturday morning, and I still have to make sure the toilet’s clean."
• Rose and Maloney starts on ITV1 in early July.