She lives with myself and my little boy, and becomes an instant member of my family.
She becomes closer to us than friends and family, therefore it is in my interest to make her happy and get her to stay as long as possible. I don't like strangers coming in and out of my boy's life and this is for his happiness and security.
I was so lucky with my first girl, who hailed from Wexford. She was a school-leaver and working for us was her first job.
She lived with us, came on holidays, and totally integrated herself into our family. We all cried when she left to work in Australia a year and a half later.
It was like a relationship break-up. Then we had a few trying months trying to replace her.
I am pretty ruthless when it comes to nannies. If they don't live up to my high expectations, they must leave immediately. I would never trust my pride and joy with somebody less than totally reliable.
A couple of girls didn't last a week. One turned up extremely hung-over telling me she'd had just an hour's sleep the night before, and another one allowed Gary to cycle on his own down a bridge even though he hadn't learned to use the brakes yet.
Then one more girl lasted a few weeks, but used to knock on my bedroom door when she came in after every night out and sit down on my bed to tell me all about her evening.
Now I understand she probably wanted to practise her English, but I tell every nanny that I am a writer and it's of utmost importance that I'm left in peace when I am writing my books and only to disturb me in an absolute emergency.
She left anyway after a while citing homesickness and I breathed a huge sigh of relief!
Now we've had the same Brazilian nanny for almost a year and she is an absolute dream.
She is living with me in Spain at the moment and her main job is to make sure Gary isn't allowed anywhere near the swimming pool.
I read with horror in the paper this week about a one-year-old in Boston who died after being in the care of an Irish nanny and my blood went cold.
That case frightened me so much, because I was a nanny in Austria at the age of 16, and the baby fell off the table and hit his head when I was changing him.
It all happened in a split second when I took my eye off him momentarily and luckily the child only suffered some bruising.
But the experience was so terrifying, and the guilt so horrific it understandably made me paranoid about choosing my own nannies.
They need to be perfect.
I trust them with my son's life, and therefore my own, too.