The Syndicate's Katherine Rose Morley on her puppy-filled audition – and whether she'll return to Last Tango in Halifax

"I remember when I first got the email through for the job, for a self tape, and it said, 'Must be comfortable with dogs.' And I circled it and replied to my agent saying, please let them know how much I love dogs."she tells RadioTimes.com.

"My boyfriend's family have two dogs, and one of them had just had puppies. And I was like: 'There are six puppies here, I've got to do a self-tape to show I'm comfortable with dogs, I'm going to get them all in.' So I used all of them. I got them all in, and they were jumping all over me." She adds: "It worked. It paid off."

And on set, there were plenty more canine shenanigans. "I mean, I almost got pulled into a lake – like, fully pulled into a lake," she says. "Because the dog who plays Duke, she is so incredibly strong, but not, she doesn't even need to kind of try, and I was doing a scene where where I was walking her, and she just toddled off. And I was almost head-first in the lake."

Across the last six Tuesdays, Katherine has been leading the cast of season four of Kay Mellor drama The Syndicate, playing Keeley Sanderson. Her character is a young, gambling-obsessed kennel worker determined to track down dastardly convenience store worker Frank Stevenson (Neil Morrissey), who has stolen a winning lottery ticket (and therefore millions of pounds) from her and the rest of syndicate, who work at Woodvale Kennels. Keeley and her co-workers are all skint and down-on-their-luck, but they've followed Frank (and his dog Duke) to Monaco – where they've since got into all kinds of scrapes.

In the first episode of the season, Keeley is celebrating her 23rd birthday – and if you've not seen Katherine on TV before, you'd be forgiven for thinking she was 23, too. But the actress is actually 31, and is no stranger to our screens; for the last decade she's been making her way up in the acting world, ever since leaving drama school and landing a roll in Channel 4's The Mill as teenage apprentice Lucy Garner. "I'll be honest with you, I've only ever played younger," she says, with a laugh. "I think Keeley might be one of the oldest I've ever played."

Since then, Katherine has had a sporadic but long-running role as Ellie in Last Tango in Halifax – and it's a character she'll hopefully pick back up again someday, just as soon as Sally Wainwright finishes writing the next season. Alongside that, she's had chunky roles in Clink and Thirteen (the TV mini-series starring Jodie Comer), and has popped up as a guest star in Call the Midwife and Vera.

But her casting as Keeley in The Syndicate is certainly her biggest role to date. And that made the wrench of lockdown all the worse; because just as filming was about to begin in March 2020, COVID hit, suddenly shutting down the UK's entire film and TV industry almost overnight.

"We'd had a few months of prepping and I was so ready to go," Katherine says. "And our first day of prep was the 23rd of March, which was the first day of lockdown.

"I was so naive. I remember the week before the actual lockdown thinking, 'I think we'll be okay, you know.' We'd had an email from Kay saying, you know, 'the BBC are there to support us, and we'll be going ahead.' And then it just stopped. And then we just did not know, when we would pick it back up, which was quite daunting, because this is such an important job for me. I feel like I've worked really hard to get to this point. To lead a Kay Mellor show on BBC One... it was tough for it to kind of feel like it was not within reach anymore."

Everyone sat, and waited... and waited. Kay Mellor re-worked her scripts and re-planned the production, moving the action from Las Vegas to somewhere a bit more local and a bit more Covid-secure: Monaco. As for Katherine, she spent her time in lockdown baking a lot of cakes. (On set, Katherine has a reputation for turning up with delicious homemade baked goods. With that and the puppy-packed audition tape, has she cracked the secret to landing a job?)

And then in August 2020, at a time when very few shows had worked out how to film in the time of Corona, a bold decision was made: The Syndicate had the green light.

"I was like, wow, we're actually doing it," Katherine says. "But I also knew, you know, friends and different people whose things still weren't happening. And there was always that doubt of going, 'Oh, we could get there, and then they tell us to shut down again.' But we were extremely lucky, that we that we did pick it back up. And it was remarkable really. It was a strange time for everybody."

It was an insular shoot, with everybody still adjusting to a new way of filming. And if the members of the on-screen Syndicate seem genuinely close, that's more than just good acting; they were bubbled together, first in Leeds and then in Monaco – where they luxuriated in the "beautiful, beautiful locations" but also spent much of their time in the hotel, restricted by a curfew. "I hope that we gained something from that. Hopefully you'll get that group's dynamic and friendship and closeness," Katherine says.

Growing up in Liverpool, Katherine was a keen performer – but somehow, she didn't realise that acting could be more than a hobby. "I just didn't make that connection," she says. "It didn't enter my head." And then the idea did occur to her, and she couldn't imagine doing anything else – which meant taking a year out after leaving school, so she could apply for drama school. Soon she was off to London, to study at the Guildhall School of Music and Drama.

Drama school was intense. "It teaches you discipline, and how to multitask, and how to keep going when you're exhausted, commitment, it teaches all these really kind of valuable lessons just as much as it teaches you any acting lessons," she says. "On the whole I really did love it." The course took her abroad, on exchanges to China and Italy: "Little me, never been anywhere before, roaming around Beijing." It gave her friendships, and contacts in the industry.

That said, "there was some aspects of drama school that you look at now and question".

One thing was her teachers' request that she speak in "received pronunciation", all day every day. "I can understand the thinking behind it of, 'It's something that you should learn. And the only way to be really good at it, is to speak at it all the time.' But I just couldn't," she says. "It felt like a long time – say three months, or a term – to lose my identity for that long. It's not who I am. I can't. I'll put as much work in as anybody else. But I just wasn't quite prepared to not be me, outside of it."

The other issue only became apparent when she bagged her first small TV job in 2012, playing a young Sharon Horgan in the Sky series "Little Crackers". "I remember being on the set, and being so panicked because I'd never been on a set. I didn't know the language. I didn't know the terminology. I didn't know anything about what it was like to be on a set. I'd never seen a call sheet before, you know, all these kind of things. And I thought, why did I not learn this at drama school? It's a classical training, which is brilliant. But that's not just what's out there."

Soon after drama school came The Mill, a Channel 4 drama set at a textile mill during the Industrial Revolution; and in 2013, she was first cast in Last Tango in Halifax, alongside such acting legends as Anne Reid, Derek Jacobi, Nicola Walker and Sarah Lancashire.

"I was very lucky to be in that. In that situation at that time, just as I graduated, not knowing what I was doing, pretending I knew what I was doing," she says. "We're all doing it: fake it till you make it. But I was surrounded by all these people who were artists, and the absolute best of the best. And I think that's stood me in good stead, all these years later."

Last Tango has allowed her a chance to grow through playing a character. "I look back I think I look like such a baby," she says. "It's so funny. I mean, it's incredible – what a gift to be able to kind of have that longevity with a TV show that is so well loved. And I love the progression that that all all the characters have made."

She adds: "Like all the audience and people who tweet us all the time, we have our fingers crossed, that it will go again, because we just absolutely adore it. It's the most beautiful and wonderful show." But I can't pry any inside knowledge out of Katherine: "We find out, honestly, not that much before – I think probably Annie and Derek know. I think she's in touch with them a lot, but I think we'd find out when it was about to go." Will she clear her schedule, if and when she does get the call? "Oh, 100 per cent."

Examining Katherine's acting CV, or her IMDb page, you might conclude that she's been working pretty solidly since graduating from drama school. But in reality, the actress says, there have been a couple of periods where work was thin on the ground.

"A lot of the time when you film something, it might not be out for maybe a year, 18 months," she explains. "So if you're on a television, people think you're busy. And the reality was it in that I've had to two periods of very long unemployment.

"The first time I struggled a lot... I think it was maybe three years after drama school. And I really struggled with it and went home [to her parents' house in Liverpool] and didn't quite know how to handle it.

"And then it happened again, a couple of years after that... and I was much better that time. I was more productive in that time, and kind of thought 'Okay, strap in, we've been here before. I'm not going to let it get me down.'

"I can't lie. It did get me down. But I was prepared for it this time around. And I never let myself feel the sadness that I felt the first time around, because I didn't like feeling sad. You know? I always try and see the positive in something. So I kind of refused to let it get me down again. Because it really did take a chunk out of my life that was I didn't enjoy."

Accordingly, she she started her own granola company – "and for a very short time it was really successful," until the acting jobs started coming in again and the granola project was abandoned indefinitely. But if you ask nicely, Katherine might still make you up bag of tasty granola – or a cake.

In the interview, Katherine mentions in passing that she's building a house. After absorbing this, I circle back. She's building... a house from scratch? Yes, apparently so. Just don't tell Kevin McCloud.

"Do you know what it was, is that my boyfriend we love Grand Designs," she says. "And I think I've watched too many Grand Designs, because it's given me a false sense of security that I could actually build my own house." The roof is about to go on; stressful decisions are being made.

But as for the idea of actually going on Grand Designs itself, Katherine baulks. "Kevin scares me too much," she admits. "No, he'd scare me. I couldn't have Kevin judging me. If you watch it, sometimes he stands back and a little bit. And I'd be like, 'Oooh, Kevin doesn't like it.'"

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"It's the same with Bake Off. Bake Off is probably my absolute all time favourite show, but I could never ever in a million years do it because, the pressure's too much. I'd like to do it from a distance, without Paul Hollywood telling me off, and Kevin McCloud – no, too much."

But starring in a BBC One primetime drama? Now that's a piece of cake.

The Syndicate is available on BBC iPlayer. Take a look at our other Drama coverage, or find out what else is on with our TV Guide.