It is hard to imagine anyone less reminiscent of the character she is renowned for playing. Where Pat is all wounds and bristles, Pam exudes the bracing self-confidence of the home counties headmistress. She has already climbed boldly (given a recent back strain) across the rear end of a chair, to enable the photographer to catch the last of the fading midwinter light. She has also given the following admirably no-nonsense explanation for why Pat always seems to be lighting or putting out a cigarette.
"Early on, when I was trying to build up the character, I thought, `She's voracious: she'd probably put everything she could get her hands on into her mouth.' " Pam St Clement emits a salty chuckle. "The tabloids wouldn't print that. Isn't it funny that they're so prurient and at the same time so prudish?"
Once happily seated, she reveals the sort of danger a high-profile EastEnders storyline can put you in. "I've nearly caused a number of car accidents in the last couple of weeks - people recognise you behind the wheel and they just stop driving. When Mike Reid [long-lost screen husband Frank Butcher, whose threatened return is the lucky horseshoe in Albert Square's Christmas pudding] first left it really was amazing. I remember driving along a motorway and people could see it was me - God knows how - and they were holding up placards saying, `Have you found Frank?' "
"The trouble is," Pam adds, brow furrowing rapidly, "they were driving badly in order to do it, and being an advanced motorist I'm a little bit fussy about that sort of thing." My grandad was an advanced motorist, and he used to cover up his insignia whenever my gran drove. Pam St Clement nods approvingly: "You get given a little white plastic cover and you have to use it, because in all fairness, if the person at the wheel is not an advanced driver, they haven't earned that badge." Has she ever covered hers? "No, because nobody else drives my car. But she would? "Oh yes, absolutely."
Conversation is just moving on to the way "people feel like you're their property, because you spend so long in their living-rooms" when an apologetic waiter approaches with a request from a wedding party next door. Pam had apparently crowned the bride Watford's carnival queen some years earlier, and a photo opportunity (with which she later good-naturedly obliges - "cheer up, it's a wedding, not a funeral") would be the icing on the newlyweds' cake. Does this sort of thing make it hard to be a normal human being? She smiles through her hors d'oeuvre - "You can't be a normal human being".
Pam St Clement's early years probably did not predestine her for normality anyway. Her Mum died when she was very young. Her Dad proceeded to leave behind his unhappy origins in an East London orphanage to become a successful businessman and marry "several" times. How many times? "Well, four to my knowledge, but there is a possibility that I have a step-brother somewhere I don't know about ... I was very fortunate in the end. I was always being farmed off to holiday homes, then when I was just pre-teens I went down to Devon to some people who were very good at taking on youngsters, and what originated as a business arrangement became my home."
She was sent to board at a private school on the South Downs ("that'll ruin my street credibility") where she was, by her own admission, "very naughty". Pam St Clement is uncharacteristically reticent about the specifics of her teenage rebelliousness, perhaps with half an eye to a future autobiography, planned to encompass "everything which was left out" of her recent appearance on This Is Your Life.
Once she'd been "hit" (Michael Aspel pounced on set during a particularly unconvincing bit of specially written dialogue with Pauline Fowler, and Pam thought the red book was meant for Wendy Richard) a representative of the show stuck by her side every step of the way to the studio: "They could see Channel tunnel written across my forehead". The ensuing programme made it sound like she'd done more than her fair share of pre-EastEnders provincial rep due-paying. "It wasn't all that bad," Pam smiles. "But the audience loves to hear that sort of thing."
When asked to make a long-term move into Albert Square after a three- episode trial she had some reservations - "I couldn't envisage how this character, who creates absolute havoc everywhere she goes and is not at home with herself or with anybody else in the Square, could possibly fit in" - but fancied the challenge. "Julia [Smith, EastEnders producer and co-creator, also of Eldorado legend] said: `We've only seen one layer of the onion skin - the defensiveness - now we'll start to peel away more and get to the vulnerability that lies behind it'."
This is pretty much what has happened, to the great general satisfaction of all concerned. Soaps seem to be the one dramatic arena in which women are guaranteed to get the best parts. After a brief semantic quibble ("I call them on-going dramas - soap is shorthand really") Pam St Clement is happy to agree. "They do tend to be the stories of women and their men," she explains. "If you have a story which is home- and environment- based, not office- or police station- or fire station-based, it has to be female-led, otherwise it just doesn't function. If it's male-led, it becomes something else, more like an adventure story. You know something is going very wrong if you're getting too many car chases."
Sometimes watching EastEnders you can almost feel the writers getting all excited at the prospect of a bit of rough-and-tumble. "They think they're writing a film," Pam smiles indulgently. She has none of the edginess you'd expect from someone who has had a pretty rough ride from the media over the years.
The tension between EastEnders' massive popular following and its potential for matriarchal subversion tends to bring out the worst in the tabloid- running dogs of patriarchy. As a reward for her integrity in being open about being gay, Pam St Clement has suffered more than her share of vitriol from the Garry Bushells of this world. "Oh well, Garry Bushell's a joke, isn't he?" she says cheerfully. "He's yet another tabloid writer who wants to be a personality without doing anything. He's actually about as charismatic as a cold chip."
Does she agree that EastEnders' recent attempt at a lesbian storyline suffered from seeming to follow the pack rather than lead it? "I think they realised there was something missing," Pam observes sympathetically, "but having given themselves that brief they didn't know what the fuck to do with it. I think Michael Cashman made Colin so successful because he is a gay man. I'd never argue for somebody having to be a part to do it - you don't have to be a murderer to play Othello - and I think the two young girls did what they could, but they couldn't really give the programme any help."
Pam has no qualms, however, about the new and distinctly glamorous face of on-going serial lesbianism. "This is probably just me," she says, "but I don't want to see a lot of people in dungarees and Doc Martens - I don't think that does anyone any favours. There is a tendency among a lot of alternative groups to stereotype themselves, but I think the most attractive thing in the world is ambivalence. People have known that for a long time - that's why drag has been around for ages."
Frank Butcher, the living antibody to ambivalence, has not been around for ages, but he'll be back tomorrow, and the evidence suggests carols round the tree will not be the order of the day. Having worked on nine separate episodes in the space of six days last week, Pam St Clement is understandably keen to put her feet up - it's a good job her driver is waiting in the lobby. "I think in many ways we provide a public service," she laughs. "People might think they're having a pretty bad Christmas until they see what we're going through."