'I just hope I've made the right decision. It still pains me. The decision still pains me.'' Raquel Cassidy is holding her head between her hands, and frankly, I'm shocked. Gobsmacked, in fact. If I weren't, I'd be leaning across the table, giving her a shake and screaming ''Don't do it!'' into her face until she relented, grabbed the phone, and renewed her contract immediately. But that would be missing the point. Cassidy is an actress, after all, and so what if she's just quit playing the best character in Teachers, the finest, funniest late-night drama Channel Four has done for years. She'll be back. Won't she?
For the uninitiated who go to bed early, Teachers initially looked like a vehicle for the post-This Life Andrew Lincoln as the feckless new boy teaching English in a Grange Hill-size comprehensive. Over two series, Lincoln and his gang of terminal adolescents barely out of short trousers themselves, shagged, drank, and swore their way through the curriculum, only breaking for a crafty fag with the kids behind the bike sheds.
But it was Cassidy as Susan, the ever so slightly fruity big-sister-cum-Girl-Friday of the group, matching the lads pint for pint when not buried beneath a pile of other people's paperwork, and the object of at least one schoolboy crush, who very quietly stole the show. I've already 'fessed up to being a fan. A low-key ''Yay!'' is the delightfully jolly-hockeysticks response.
''I loved doing Teachers,'' she says, looking, with her oh-so-London shades perched on a trendily hennaed hair-do, as un-Susanish as possible. Cassidy is slighter, smarter, a little bit posher and just as dryly, one-liner funny, even with her children's entertainer stripey tights hidden from view beneath the table.
''I don't know if it's set me on a road, but it certainly got me out of financial penury for two years. But as much as I love it - and it's a huge sacrifice - as much as I love it,'' she says again, ''I'm in acting because I'm searching to do lots of different things.''
School's out forever, then, and Cassidy's bunking off in Glasgow to play Joyce, a woman of many parts in John Mighton's play Possible Worlds at The Tron. The flagship production of the theatre's Six Stages festival of Canadian theatre, the play is essentially a hydra-headed murder mystery, in which a man's brain is stolen. Delving deep into his imagination, Joyce is his one constant, who nevertheless appears in different guises. Sometimes she's a one-night pick-up, at other times she's his wife and first love. Not so much the romantic lead as a fantasy figure of parallel lives, its exploration of free will in a world of multiple choices all sounds very Sliding Doors, with Joyce always different, but somehow always the same.
As an actress, Cassidy is all too used to being other people every day of her life, but its not just onstage you see a different side of her.
''It's a play partly about finding out who you are,'' she says evenly, ''and, you know, I'm different with different people. I sometimes wish that weren't the case, but I do metamorphosise, and sometimes that's a pleasing thing, and sometimes that's an unsettling thing. It depends on who you're with, whether you're in awe of them, whether you respect them, whether you are frightened of them, fancy them, want to work with them, really don't want to spend any time with them at all; have been with them, haven't been with them, whatever.'' She bites her lip, looking slightly kooky, if utterly self-aware as she lets her guard down. ''I've talked myself into a bit of a cul de sac there,
Born to a Spanish mother and an Irish-Mancunian father, Cassidy grew up in sleepy Fleet, in Hampshire. As the youngest of three children, and the only girl in the family, she was pretty much left to her own devices.
''My fantasy life was very full. Certainly when I was a kid, I probably wanted to be an actor because I wanted to be a princess, or something magical, and get to dress up magically, and have the kind of life that I hadn't been born into, with magic powers or whatever, and live this wonderful idealised life. To an extent, maybe even as an adult, I don't know how much I've grown out of that.''
A magic trap door at the bottom of her bed led her off into all manner of secret adventures.
''I wasn't consciously acting. I was kind of living those things, that dream, what it would be like.'' She bites her lip some more. ''I've never told anyone that before,'' she says, sheepishly amused. From school plays - ''Teachers notice that you've got a bigger gob, or are less frightened, or are more excited'' - to university and a potential career working in developing countries. That plan was thwarted - after a year of decision-making - by the usual round of tuppence ha'penny, if increasingly prestigious, pub theatre shows, including a turn in Anthony Neilson's controversial play The Censor.
SHE says: ''Before I was cast as Susan I used to play people who were really different,'' she says, ''but not necessarily different from me, because there's everyone in everyone, so we all have the possibility to be everyone and everything. If you see what I mean.'' And she's off down that lip-biting cul de sac again. ''But I did used to play a lot of really bonkers mad women,'' is how she eventually puts it a whole lot more succinctly.
The week before going awol to Glasgow, Cassidy finished filming Red Cap, a new drama set among female military police officers, starring Tamzin Outhwaite, and due to be broadcast next month. Such a move into prime time might suggest Cassidy has her sights set on top light entertainment, but it's a notion with which she begs to differ.
''While Teachers may have had its following,'' she points out, indulgently schoolmarmish at the prospect of being recognised on the street, ''it was on late-night Channel Four, whereas EastEnders was seen by millions and millions of people. I certainly don't have the cache to sell a programme like that, and certainly nobody's coming up and asking me to.''
Cassidy expresses a desire to work in independent cinema on the continent, while her features seem tailor-made for grit and sawdust-quality Brit-flicks a la Michael Winterbottom and co. Significantly, she's only ever been cast onstage in two classical roles (Desdemona in Othello and Viola in Twelfth Night), and would prefer to bodyswerve blockbusters.
''I went to see Men In Black 2,'' she recalls, making a face, ''and it was just a commodity, just money being shifted.'' She did enjoy SpiderMan, however, ''because we all want a superhero to come and save us, but in the end he doesn't, so hooray!''
Flipness aside, Raquel Cassidy takes her acting seriously, which is the reason she's in Glasgow in the first place.
''We are kind of on a search in that way to express . . . something,'' she says, risking a furrowed brow. ''Potentially you do inhabit different worlds. And while there are no specific roles I'm burning to play, as far as acting in the future goes, I'd really like to have done searing work.''
Cassidy ponders this statement a moment, biting her lip all self-conscious again, angsting over chucking Teachers some more before recovering the strength of her convictions. ''Searing work,'' she says again, relishing her future prospects, whoever she might be.
Possible Worlds runs from October 10-26 at the Tron Theatre, Glasgow.