"The world revolves around white lies," Lindsay admits. "I think if we all told the absolute truth, the world would fall apart. But Kathy's is a big lie and it's nothing you would ever expect from her. I went cold when I read about it. It was just so brilliant," she chuckles of the screenplay penned by the Bafta and Emmy award-winning writer, Danny Brocklehurst (Accused, Shameless).
"This woman is desperate. She thought she could compartmentalise the lie like she does everything at work, that she could put it into a box and file it away and no one would find out. I felt for her when it all fell apart because she seemed to have it sorted."
The car showroom's offices act as a microcosm for life. There's Beesley's ambitious, sleazy boss Mike, the hot blonde head of admin Beth (Jo Joyner), the salesman Marty (Jason Manford) who says his wife has died to keep his job, the young-gun salesman Pete (Mackenzie Crook) and the young party girls Tracy (Michelle Keegan) and Viv (Cherrelle Skeete) who can't wait for the weekend.
Kathy tries to keep it all together in her motherly, though slightly dour, way.
"She has been at JS Motors since she was 17," Lindsay explains. "She's happy with herself. She's very bossy, she knows everything about everyone and she wants to know all the gossip. She's got a lovely husband at home and her kids are at university. She's made it. But then something happens."
Of course there's never been a greater hotbed for shenanigans than in the theatre or television industry where Lindsay started out. Just think about it: she could have worked with those greatest of liars, Rolf Harris and Jimmy Savile. "I've never found anything out on that level," she admits.
"To be honest I'm not a gossip at all. People would be having affairs at work and I wouldn't know. I'm absolutely rubbish at that," she quips, emphasising her Mancunian accent.
"People would tell me afterwards or I'd find out in the papers. I don't know if I've been so knackered because of the kids, but I'd just go to work, have a lovely time and come home."
Lindsay is a kind of national treasure in the UK. There's no doubting that her presence in Corrie resonated as strongly as it did because she's the real deal.
She was born and raised in a Manchester terrace house like the ones in the show. She's also a Mancunian made good.
She was at university studying English - "I got a degree, not that I've used it much" - when she appeared in a play and discovered her acting talent.
"I was 24 when I got my first job in Dangerous Liaisons. I did a bit of telly and then I went on a year-long theatre tour. I was 26 when I started Corrie so it was pretty quick for me."
At 37 she became a mum to twin boys with her drummer husband, Steve White (most famously from The Style Council), whom she'd been with 11 years, though they only married in December 2013.
"It's not really late to have kids in my industry because we have to establish our careers first," she explains. She already had grown step-kids but having twins proved enlightening.
"I think it's the biggest lesson ever because you have two children at exactly the same time and mine couldn't be more different, looks-wise, personality-wise and in the toys they like. Yet I've brought them up exactly the same. You worry yourself sick but they're pretty much cooked when they come out."
She is also busy working, often playing the effervescent types of characters for which she has become known.
"I'm about to shoot [the series] Still Open All Hours where I'm a very snappy fishwife and we've just done the fifth season of Mount Pleasant where I play Lisa who's bubbly but spoiled. She's the lead in that and very in charge of everything."
Even if she's well known, Lindsay is not bothered too much by the paparazzi.
"When I came to London from Manchester I was chased down the street a few times back in the day, but they don't bother with me any more. I still think it's ridiculous.
"I don't want to see Kate Middleton in the nude. I don't know that we need to get that shot of somebody who's just had a baby. I find that all just a bit sick, really."
• Ordinary Lies premieres on TV One tonight at 9.30pm.
