Lionel Shriver: Have you ever read a headline that praised a social worker?

They butt into a family's private business, paid to be mistrustful

Carte blanche entrée into private homes. Exposure to the scintillating underside of human nature. Permission to ask prying, even embarrassing questions. A treasure chest of bizarre or heartbreaking stories, an inexhaustible trove of "material". As a fiction writer, I sometimes envy social workers. For two seconds.

When did you last read headlines like "Social worker lauded for rescuing child from violent parents" or "Nobel Peace Prize awarded to social worker who brought harmony to council estate" or "Neighbourhood mourns passing of beloved social worker"? Not recently? Well, how about "Social Services condemned over four-year-old's life of torture"? Now, that is familiar.

It's from Friday's paper, of course - about the sentencing of Samuel Duncan and Kimberly Harte, who abused their daughter, who had cerebral palsy. They scalded the girl's hands with boiling water, kicked her repeatedly in the groin, pulled out clumps of her hair, and locked her in the loo to sleep naked by the toilet. But later the fact that "Child B" was in so much pain that to be examined by a doctor she had to be put under general anaesthetic will soon blur into that undifferentiated mass of horror stories about kids who have been starved, raped and dangled over flaming cookers while social services made blithe, credulous little visits.

I'm not necessarily defending Westminster council's child protection system here. "Child B" had been removed from parents suspected of being violent, and returning her was - easy to say now - a mistake. It does seem odd that social workers could have called on the family 20 times and not noticed anything amiss. Yet this is an apt enough juncture to consider that social work is so thankless, underpaid, and perilous (no doubt physically so, on occasion) that it's amazing we can con anyone into the job.

Everybody hates you. You're employed to butt into a family's private business, and you're paid to be mistrustful. Because you're empowered to do dreadful things such as take children away from their parents, you're perceived as a threat. No one looks forward to your popping by. You routinely confront either raging hostility or artificial, brown-nosing ingratiation, and either way it's hard to get straight answers in, what - 20 minutes? You can't spend long on a case, because you have a whole rota to get through in one day. How many of the people you are trying to help will not answer the door or will treat you like rubbish? How many of these cases will be deeply depressing? I've never fancied public service - not with the kind of public that routinely screams, brawls and curses outside my window.

Yet the stakes are frighteningly high. Suppose you are harried and tired and, yes, you accept the explanation from Kimberly Harte that, sorry, you can't see her daughter because the kid is away with her father. Failing to flip through the file and note that the mother has said this four times in the past, you decline to become pushy and unpleasant. You're running late (again), and the traffic is terrible (again). The woman seems personable enough, and the house isn't a tip.

Your mind is already drifting to the next appointment... where something tells you that the foster father is a heavy drinker, but he's seems to be sober whenever you drop by and you've no way to prove it... So you give Kimberly Harte the all-clear for now, and scribble a note about how somebody has to call back soon when the child is home.

Consider the kind of life these poor blighters lead - unwelcome, resented, shunned, never given any credit. But first to be blamed if something goes wrong. For what happens? It turns out "Child B" has been kicked so hard that she has liver damage. Everyone is pointing the finger at you; you're all over the papers. And not for winning the Nobel Peace Prize.

Lionel Shriver's novel 'The Post-birthday World' is published by HarperCollins in May