Perdita, the Lawyer's new assistant, is one of those odd people who have made the leap from other, sometimes real, jobs, to solicitor
She was an NHS psychologist, but says she gets infinitely more job satisfaction from the law: although she's still sitting in stuffy rooms listening to people's problems, she now gets paid properly for it.
"Money equals esteem. No one thanks you for doing a public service any more," she told me as she helped stack the dishwasher after dinner.
"I bet they're wary of you, though," I said.
"Yes, but the whole department's like a dysfunctional family," she replied. "They're all at war with each other and in denial about the whole thing, so they've barely noticed that I've arrived."
"Ah," I said, wondering about my own dysfunctional family: all of our children made an appearance during the dinner party, demanding snacks and drinks and, in six-year-old Liability's case, that we switch on Graham Norton, and each was simply ignored by my husband until they started throwing the sherry trifle at him.
"Yes," said Perdita, continuing, "take the fact they haven't won a tender in about six months. They're all frightened someone will a) notice, and then b) pin the blame on them, so they're all taking different evasive action.
"There's the head of the department - dysfunctional dad if you like - who gets angry and starts shouting if anyone raises the subject, and mutters darkly about disloyalty and how you can't trust anyone any more.
"And dysfunctional mum is that guy with the funny hair who covers up for the department by working 18 times as hard as everyone else. He's always in the office at weekends and won't take a holiday, and he's needlessly helpful - always buying you sandwiches and tidying up your desk for you."
"God, I know!" I said.
"Then you've got the moody associates as defensive teenagers who think they'd be happier if they were at a different school - they're the ones who take half an hour out of your day telling you why it wasn't their fault but no doubt they'll get blamed anyway, and they wish they'd gone to Jenkins & Bloggs instead, as they don't treat people like that there.
"And there's also a kid in the treehouse - the one who goes off and works on his own and won't tell anyone what he's working on and leaves everyone in the dark when he goes off on holiday. And if you try to get him down, he starts lobbing rocks on your head - you know, wrecking everyone else's work and refusing to pass on information, that sort of thing."
"Oh yes, I know him," I said.
"And there's a couple of gin-sodden aunties and hypochondriac uncles, who conceal the fact they haven't charged more than a day's work in six months behind their hangovers and their hernias. And then there's what we call the mascot: the one who can't bear to see everyone so unhappy. He tells jokes all the time and tries to get everyone to come out for after-work drinks and generally runs around distracting people so they won't notice the department's going down the tubes."
"Ah," I said again, for I could hear my husband in the next room publicly demonstrating his golf chipping with the help of the coal bucket, a candlestick and a spare satsuma.
"Oh God, not your husband!" said Perdita. "No, if anything, he's the child who thinks he must have been adopted, and he can't understand what he's doing in this family at all. Secretly, you know, he thinks he's royalty."