The girl's name is Josephine, but her English parents call her Joe Egg after a saying of her very English, very suburban-provincial grandmother's: "Just sitting around like Joe Egg." Young Josephine does nothing but sit around; she has cerebral palsy. The parents, Sheila and Brian ("Bri"), made the decision about 10 years earlier to care for her, though she would never be, as Sheila puts it, more than "a kind of living parsnip." Peter Nichols' graceful and well-formed drama, based on his own experience raising a child with cerebral palsy, dates from the '60s, but it's been revived twice on Broadway, most recently last year with Eddie Izzard. TheatreFirst's small-scale production at its new Mills College home has a surprisingly intimate, real-life feel; director Clive Chafer -- with the energetic help of Simon Vance as Bri and Cynthia Bassham as Sheila -- has re-created the mood of 1960s London with touches as subtle as clothing (Bri's elbow-patched coat) and makeup (Sheila's blue eye shadow and straight hair). The show does lose momentum in the second act, in part because Howard Dillon and Jessica Powell, as a pair of snobbish upper-middle-class Londoners, put on broad caricature performances that might work in a middling BBC sitcom but seem out of place here. Wanda McCadden, though, as Bri's petty fussing mother (who uses the Joe Egg phrase), is brilliant, and so is the young Miranda Swain, who seems to have studied cerebral-palsied girls in order to play one with so much vivid sympathy. After almost four decades, Joe Egg has not lost its power to shock or entertain; it's a witty and nimble exploration of what even humanists mean by "human."