Countess Cora: a rock chick at heart

When she hasn't been donning 1920s finery for her role as the refined Countess Cora on Downton Abbey, actress Elizabeth McGovern has been fronting a band. Although, she is quick to point out: "It never was Cora suddenly being in the band, it was this person in a band suddenly being Cora."

After years of playing guitar as a hobby, strumming along to Bob Dylan, Joni Mitchell and Leonard Cohen, in 2002 McGovern answered an advert offering guitar lessons. Her teacher, Steve Nelson, became her bandmate in Sadie and the Hotheads, and under his guidance the songs poured out. "I was amazed to find it so comfortable", she says "because I've never thought of myself as a writer; I've sometimes thought, because I've spent so many years reading scripts and plays, that I should try and write one, but I couldn't even fill up half a page. For some reason I sat down and these song ideas poured out of me."

McGovern, 51, is in rock singer guise today, black jeans and silk shirt, when we meet in Chiswick, west London, near where she lives with her husband, the British film director Simon Curtis, and their two daughters. Sadie and the Hotheads' debut album was released in 2007, but its October follow-up How Not To Lose Things has been given a considerably bigger push in the wake of her increased profile thanks to Britain's most successful TV period drama since 1981's Brideshead Revisited. A tour is scheduled for February. She played the penultimate night of her residency at London pub The Troubadour. Reviews have been mixed, and not all will be won over, but there's a certain charm to the unpolished, husky vocals McGovern stamps on her country, down-home folk, rock 'n' roll and lounge-jazz songs. And McGovern isn't interested in delivering perfect renditions.

"I'm not the greatest guitar player, I'm certainly not the greatest singer in the world, but that's not what it's about. It's about connecting. It's very idiosyncratic. You either will love it or hate it, but it's genuine." For her, Sadie, which began as an alter-ego, is all about expression – you could say the antithesis of her fictional family, the uptight Granthams. "That thing that's inside everybody, their true voice, and if there's anything that gives me great happiness it would be that my music connects to people in a way that they can have confidence in their inner Sadie to do whatever it is they do."

The self-expression that the band affords also makes a diversion from acting. "As an actress, I've always tried to embody somebody else's vision as best I can. With the music it's a whole different thing: I'm serving my voice. And it's taken me 40 years to find that voice." That voice is the "50-year-old woman waking up after 20 years with a great guy, watching her kids grow up, tending to the day-to-day monotony of existence. There's not a lot of music being written now for someone who's in a time of life that isn't angst-ridden and I'm really interested to see if people can relate to that".

The world of muddy festival and pub performances are a far cry from her glamorous Hollywood past. Before she started her music career at pub-based open-mic nights, McGovern lived in New York and Los Angeles where she cut her teeth in films while becoming one of Hollywood's hottest young properties. At 19, she won an Oscar for Best Supporting Actress in Ragtime, and she starred in Ordinary People, and in Once Upon a Time in America with Robert de Niro. Later, she came over to Britain to make Christopher Hampton's Tales From Hollywood, and met its producer, Curtis, and soon after, moved here.

For someone accustomed to the glamour of Hollywood, how did she find performing in London's dingy pubs? "So fun!" she exclaims, "because I could just leave everything that was my preconception of myself behind. Nobody cared about who I was or where I came from, and I found that incredibly liberating. I don't believe I would have done any of this had I stayed in the life I was leading and I had this weight on my shoulders which was my identity from when I was a teenager. I just felt I could recreate myself."

While it was an easy decision to move country, it wasn't so easy in practice, and it wasn't helped by the fact that it coincided with some of life's other great milestones – marriage, pregnancy, and giving up a career, all in the space of six months. "It was a split-second decision and it was difficult to accept the decision I'd made afterwards. There was a lot of processing I had to do." What she wasn't prepared for was finding herself an outsider among British people, unable to understand the intonations and quirks, and the differences in culture, in particular, the coffee – or lack of it. "When I first came over you just couldn't get a decent cup of coffee. And I know there is a God because a month after I was here I got down on my hands and knees and prayed for Starbucks, and now there are three on every corner."

This summer her British-born children watched their mother perform at the Isle of Wight festival. It was the first time McGovern felt that she wasn't a source of irritation and mild embarrassment to her children who have slammed the door to avoid her constant practising around the family home.

It's impossible to avoid the incongruity of McGovern's double life as Cora and a rock singer. Would she make the transition from filming Downton Abbey to heading straight to gigs? "No", she says with that recognisable polite, sweet smile, "but Michelle Dockery and I used to hike up our skirts and go into my trailer and sing together and work out the harmonies for all the songs. I could hear her singing to herself on the set, so I lured her into my trailer." Dockery's backing vocals feature on six of the album's songs. Still, McGovern likes to keep the worlds of Downton and her band separate. "I genuinely try to keep my brain on Downton Abbey when I'm there because it is a different way of thinking."

For now her focus is directed towards her biggest goal for the band: making it financially viable, to the point where she can pay her band for playing. I suggest merchandise, and for a second she looks horrified. "I think I've made the mistake of being insensitive about the business perspective, as if it's too crass to consider it, and now I really understand the necessity. Merchandise, bring it on baby, sell my soul! Whatever it takes."

Sadie and the Hotheads are on tour 8-18 February sadieandthehotheads.com; The Downton Abbey Christmas Special will be shown on ITV on Christmas Day at 9pm