Trollope's spoonful of sugar

I am starting to think of Joanna Trollope as the Mary Poppins of modern fiction.

You recall the scene in the movie where Julie Andrews as Mary decides it is time for the children, Jane and Michael, to take a dose to clear out their little insides? And they make all sorts of horrible faces, but when the medicine passes from the spoon onto their tongues, it turns out to taste of ... mmm, strawberry ice, lime cordial or, when Mary administers a spoonful to herself, rum punch. Delicious!

And then she bursts into a song in which nannyish admonition is perfectly blended with fascinating coloratura arpeggios and a potent infusion of well starched sex appeal. A spoonful of sugar, she carols, makes the medicine go down ... in the most delightful way!

Well now, whenever I crack the spine of a new Trollope, with its discreet jacket design, silken bookmark and handsome modern classic typeface, the spectre of Poppins floats into my head.

Here is her latest novel, Girl From the South - "an exciting new departure for Trollope", says her publisher - and in my mind's ear there comes the sound of roguish arpeggios of virtuoso rectitude.

Every Trollope has its fascinating moral wrinkle. She has a glorious instinct for sensing which emotional conundrums her readers will find most palatably perplexing. And then she writes so beautifully. She is not shrill, she does not batter you with her views; she offers questions, not answers, in a style so graceful and judicious that you would call it restful if it were not also palpably intelligent. What is more, she likes men as well as women, and quite often takes their side.

The Girl From the South is about commitment, and the difficulty that thirtysomethings find in making it. As a subject, it lacks the freshness of some of Trollope's earlier fictions - the ground is well marked already with the spoor of Helen Fielding and Tony Parsons - but that hardly matters when there is so much to say about it. The framework of the story is triangular.

The narrative passes between Trollope's hero, Henry, a wildlife photographer, his girlfriend, Tilly, a features editor on an arts magazine, and Gillon, an arts graduate from Charleston, South Carolina, who hasn't quite worked out what she wants from life, and consequently spends much of her time fleeing her Charleston roots and then being drawn inexorably back.

Gillon is in flight mode when she encounters Tilly at a grim London party. Lonely and alienated by the mess and indifference of London life, when Tilly invites her to become a lodger in the Parson's Green flat she shares with Henry, Gillon is keen to accept. Henry, on the the other hand, is irritated and perplexed by Tilly's offer. She has only just insisted on sacking their previous lodger, Henry's old university friend, William, on the grounds that their relationship as a couple can't move on while they have a live-in spectator to their domestic drama.

Reluctantly, he agrees to meet Gillon. It is dislike at first sight. I dare say you can guess the rest.

Of course, there is more to it than Henry and his love life. Commitment is a complicated subject and Trollope explores all the countless permutations of her chosen subject with efficient relish. She anatomises decaying Southern belles and their amusingly forthright old black housekeepers, psychiatrists with a chip of ice in their hearts, Good Ole Boys of all ages, jaded Sixties beauties and charming, muddled, wayward young men until we can peer into every crevice of their flayed emotional cadavers.

She does this with such elegant precision - revelatory and ambiguous at just the right moments - that it seems quite ungrateful to complain that many of the characters seem more like very good waxworks than actual flesh; that choreography, rather than the fractal naturalism of genuine emotional encounters, seems to order the advances and retreats of the plot; that the entire exercise, in short, seems a trifle mechanical - sprung, like some technically perfect ètude, from an impulse which is not quite that of sheer joy in invention and writing.