The first sign that something was wrong with Ludo was when he complained of a tummy ache. This was after school and hardly a rare occurrence so I didn’t think anything of it. The following morning, he still had a tummy ache. Not a good enough reason to miss school in my opinion, but Caroline thought otherwise. Before I left for a meeting I told him to eat some toast. ‘You’re probably just hungry,’ I said.

By lunchtime the pain had become localised on the lower left-hand side of his stomach and Caroline decided to Google his symptoms. It sounded like it could be appendicitis so she took him to the GP and he advised her to take him to paediatric A&E at Chelsea and Westminster. The paediatric registrar who examined him thought there was a ‘60 per cent chance’ it was appendicitis and booked him in for surgery. That was just as well, because by the time they wheeled him into the operating theatre his appendix had burst.

We’d been at this hospital once before with Ludo. When he was a few days old Caroline came out in spots. It was me who got on the internet on that occasion and my conclusion was that she had chickenpox. That was bad news, because if a mother presents the symptoms of varicella-zoster virus in a seven-day window from five days before to two days after delivery, her child’s life is in danger. Left untreated, the mortality rate for neonatal varicella is 31 per cent.

Ludo was fine in the end, but it was touch and go for a while. In spite of being given some antibodies, he caught chickenpox and the low point was when his temperature suddenly shot up, indicating the virus might have spread to his brain. I remember holding him in my arms that night, tears streaming down my cheeks, offering to make any number of sacrifices if God would make sure my son was OK.

I was reminded of this on the evening Ludo had his appendix out. We went to ‘recovery’ to see him as he came out of theatre and on the way back to the ward we passed the chapel. I glimpsed a woman on her knees, presumably the mother of some poor child. They say there are no atheists in foxholes, and they’re pretty thin on the ground in paediatric wards, too.

Strangely, there are some benefits to having a sick child. For one thing, all your other problems suddenly seem like very small beer. Any anxieties you have about your finances or your health quickly recede into the background as the new, much larger worry blots out everything else. It’s not quite right to say that concern for your child puts them ‘into perspective’ because, in truth, those are things you ought to be worried about. It just temporarily obscures them. And this is a source of some relief amid all the anxiety. It’s like being given a holiday from day-to-day concerns so you can focus on the larger problem.

Another benefit, for men at least, is that there’s a reversion to traditional gender roles within the family. It doesn’t matter how assertive and confident a woman is, she automatically assumes a maternal role if her child is struck down with a life-threatening illness. She instantly becomes the primary caregiver, the person enveloping the child in a protective blanket of love, not a decision-maker. Similarly, it doesn’t matter how emasculated and passive a man is, he becomes the head of the household the moment his child’s life is in danger. I’m not what you’d describe as an alpha male, but I cannot help but become a bit of a caveman on occasions like this. It’s biological.

Ludo was on intravenous antibiotics for five days after the operation, a routine precaution after a burst appendix. He didn’t like that much, I can tell you, but he perked up when one of the nurses wheeled a Nintendo Wii into his room. Exactly seven days after being admitted he was home.

Eight years ago, during the chicken-pox episode, I promised God I would raise some money for Chelsea and Westminster if Ludo got through it unscathed — and so I did. There was no equivalent dark night of the soul this time round, but I’m going to raise some more money for the hospital nevertheless. It’s the least I can do now that the doctors and nurses who work there have saved my son’s life twice. God bless them, every one.