She plays Hannah, an attractive author, content to do without the attentions of men. 'It's maddening for the men around her, because they all want her. But that's the thing, the more unattainable someone is, the more they are wanted.' She should know. From The Manageress, in which she played the manager of a football team, to the boss in the coffee ads, she has developed a line in pert, twinkly, career women, who know how to keep their distance.
She swings round the corner of the National Theatre, sandwich in one hand, cup of coffee in the other. As she poses on the set of Arcadia, she discusses last Sunday's BBC programme on Fellini, shifting with poise and ease into each new position the photographer suggests. She's slim, with long, brown hair, high cheek bones, a slender curving nose, and arching eyebrows. At 40, she's brisk and bright. Halfway through, she remembers that the dress she wears in the play would go far better against the background. 'It's lighter,' she explains, with some precision. 'It's diaphanous. Cornflower blue.' She goes and changes.
Later, in the semi-darkness of the Visiting Directors' office, she talks energetically about the virtues of Stoppard, De Niro and Branagh. It's chilly in here and the overhead light doesn't work. But Ms Lunghi is undimmed. An anglepoise lamp picks up her face, rather dramatically, as she canters through her life. Damn. The last thing an interviewer wants to be is charmed.
Her father was Italian, which accounts for her name. (Cherie she pronounces sherry, not cherry.) 'I've got his lankiness.' If you can be lanky at 5 ft 5 1/2 , then she has. Her father was in the foreign legion in Algiers for five years. He married when he came to London. 'The rest,' she says, 'is me.'
She grew up in rented accommodation in post-war Kensington. 'I was the generation of children that played on bomb sites.' Her parents separated early, and her mother, aunts and grandmother lived on the ground floor and basement of a house in Abingdon Villas and rented out the rest to a bomber pilot, nurse, Scots lady and reclusive artist. 'It was an extended family.'
She soon joined another. She won a scholarship to Richmond Grammar School, but went instead to Arts Educational at Hyde Park. This was an attractive building, with Adam fireplaces, painted ceilings and a marble staircase. Her contemporaries had nice features too: they included Jane Seymour, Jenny Agutter and Nigel Havers.
She did seven years at Arts Ed (doing Alice in Wonderland on the radio when she was 13), then three years at Central. She got work; 'but I was playing people's daughters. I had to make the change.' She did 10 months' rep in Newcastle, then three in Nottingham. Then she was back in London, waitressing, before her first job at the Royal Court. This was on the switchboard. Her second job there was selling programmes, allowing her to watch Peggy Ashcroft every night. 'I was struggling to be confident.'
Trevor Nunn auditioned her for the RSC ('he had long, long hair, a beard and a fur coat. Everyone wore second-hand fur coats then'). She played a good range of parts: Perdita in The Winter's Tale, Hero in Much Ado, Celia in As You Like It. Then Terry Hands offered her Viola in Twelfth Night. 'That was a lead. That was major. That was one goal scored.' Her Viola was delightful - sylvan, impish and witty - and, at 25, she was on her way. Films were her ambition. So 'that was it with the RSC'.
Her film roles have been eclectic, historical, centred on the princess figure: Queen Guinevere in Excalibur (1981), one of the wives in King David (1985), and Carlotta, who spurns De Niro, in The Mission (1986). This month she starts filming the part of the baron's mother in Branagh's Frankenstein.
She got the Kenco ad on the back of The Manageress. She thinks she had 'a lot in common' with the football character, but when she bollocks the team you sense uncomfortably that guile and composure suit her better than authority and aggression.
She looks stronger in the ads than in the series. Ads, like film, use plenty of takes. Compare her key scene with De Niro in The Mission with a TV scene of hers, and you see a quite different level of truth. 'The pressure in television is unbelievable. Accountants with computers work out how many pages in a script and how many minutes per page, whether it's an action sequence, or an emotional sequence, or someone going up and knocking on the door.'
The coffee money allows her to pick and choose. She has a seven-year-old daughter, Natalie, from her nine-year relationship with Roland Joffe, director of The Mission. She's a single parent now. 'That's the beauty of repertoire. I get evenings when I can get home and do her homework with her.' Does she help with yours? 'No, she sees me lying in the bath talking to the ceiling and she laughs her head off and mimics me.'
'Arcadia': Lyttelton, SE1 (071-928 2252), tomorrow to Thurs and 22-24 Nov; Lyceum, Sheffield (0742 769922), 29 Nov to 4 Dec.