Pretty soon, the job advertisement of the year is going to appear in a newspaper or magazine somewhere near you. For Brad Pitt and Angelina Jolie, after the arrival yesterday of twins, have made a momentous decision. With their role call of offspring now up to six - Maddox, Pax, Zahara, Shiloh, and the newly arrived Knox Leon and Vivienne Marcheline - they have decided what any other couple with a £300 million fortune and a small squadron of young would do: hire a full-time nanny.

“I guess you reach the point where it's just a practical decision and you need full-time help,” Jolie said, recently, while stopping Maddox from knocking a wing nut into a Meccano spider-bot with her Oscar. That Brad Pitt had nothing to say on the matter merely amplifies their need - he was lying on the bathroom floor, Zahara on his chest, “making him over” by colouring in his lips with a yellow felt-tip.

There will be many who boggle at the recent lifestyle choices of Brad Pitt and Angelina Jolie. After all - and this is a question equally applicable to either Pitt or Jolie - what is the point of pulling one of the hottest people in the world, totally getting them to take their clothes off in front of you and everything, and then ruining it by moving the cast of Oliver! into the next bedroom? I do not wish to be crude here, but Pitt and Jolie are not, currently, living in Goodtime Sexyland - tumultuously pounding their way across their linen in an endless, oceanic rumpfest. No.

At 9pm - the end of Location, Location, Location - Brad will wake from a dribbly, snorty doze and say “Oh, sorry”, and Angelina will say “We could at least try”. There will then be the tremulous undoing of the top pyjama button - before the cry of “Daddy! I can't find Honk-Honk!” decisively snuffs out their guttering candle of desire for another day.

Let's be frank here: their title of the “Hottest Couple in the World” is pretty much meaningless. Currently, your mum and dad are having better sex than Pitt and Jolie. Even if, and this is sadly factual, they're dead.

So, yes. A nanny for the Pitt-Jolie massive. Who can blame them? Angelina will be desperate to go to the toilet without being interrupted by someone falling headfirst down the stairs, and Brad's got a three-year backlog of Exchange & Marts to flick through. I almost want to pay for their nanny myself. The situation of those beautiful millionaires is pitiful.

However, I can assure you, I would not like to actually be their nanny. Being the Pitt-Jolie nanny would be awful. Indeed, aside from any job where you might run imminent risk of being suffocated to death when six miles of incorrectly propped tunnelling collapses on you, I think it might actually be the worst job in the world.

For any woman or gay man - who, let's face it, are pretty much the only people interested in hanging around a load of small children all day - every aspect of the job would be torture. It would be like a modern, metropolitan version of the 12 tasks of Hercules. Consider:

1. No gossip. You're jetting around the world, watching Angelina Jolie trying to remember the lyrics to Don't Stop Me Now by Queen, and George Clooney trying to open up the heat-sealed packaging on his new iPhone charger with a bread knife - but you can't tell anyone about it. No one. You're going to be locked in a full-body Pitt-Jolie confidentiality clause so watertight that you can't even sweat. Personally, I believe someone could get to a state where they have so much unshared gossip in their mind that they could explode. I wouldn't want to run that risk.

2. For the first four months at least those kids are going to scream every time they see you. The only people they've ever previously looked at are Brad Pitt, Angelina Jolie, Matt Damon and Catherine Zeta-Jones. The first time Zahara sees your quotidian, non-Time magazine-nominated Face of the Year face, it will be as a hammer-blow to her concept of humanity. “Your lips are non-bounteous!” she will wail, in pain, clawing at her face with her hands. “Your breasts are fractionally asymmetric! What is this creature that speaks with the voice of a human - yet lives with the face of a battered Kraken? My mind burns!”

3. It's six kids. Six kids. Whatever way you slice it, the practicalities just don't add up. You have only two hands - donated, say, to Shiloh and Zahara. Even if you make Pax and Maddox hold on to your cardie, you're still left to steer the final pair of Pitt-Jolies across the road with a series of, to be frank, kicks. There's a reason why, 100 years ago, when all women had huge families, they tended to die in childbirth around the fifth baby. It's that they just couldn't bear the thought of trying to get them all up an escalator with a buggy.

4. This nannying job will have fairly fluid boundaries. Let's face it - the Pitt-Jolies are people who collect humans like other people collect small porcelain frogs. At any minute they could suddenly tire of purchasing immature samples of the species and start collating adults instead. Given their proclivities, you could easily walk into the nursery one day, only to find Nelson Mandela sitting on a beanbag waiting to sing The Wheels on the Bus. That would be weird.

5. Aniston. Despite Brad's ex-wife appearing, by all accounts, to be a fairly well-adjusted person who is getting on with her own life, this is Hollywood. All we have learnt in the movies tells us that, at some point, a jealous and demented Aniston will drag up as a man, apply for a job as a gardener in the Pitt-Jolie mansion, and gradually convince Pitt that he has gay love for her. You'll be the one picking up the pieces as Jolie lies on the floor, screaming “THE BETRAYER IS MANISTON!”

Do you want that? All that? To be honest, you'd be better off just doing data input in an office, until something else comes along.