I thought I had one of those myself in a deeply regretted incident at breakfast on the same ferry, when my little son would not let me have a bite of his croissant and I ripped the damn pastry up and threw it on the floor. She said that no, the medical term for that was a 'drug hangover', or perhaps it was just the fact that an overnight ferry was not the best place to begin a diet. We then considered the holidays with children that we have known.

How much do doctors drink? "Lots," she said.

Why are the McCanns saying they didn't sedate the child? "Why do you think?" Besides, it was completely possible that the child had been sedated and also abducted . . . which was a sudden solution to a problem I did not even know I had: namely, if the girl in the pink pyjamas was being carried off by a stranger, why did she not scream?

Sedation had also been a solution to the earlier problem of how they could leave their children to sleep unprotected, even from their own dreams.

But sedation was not the final answer, after all.

If someone else is found to have taken Madeleine McCann . . . as may well be the case . . . it will show that the ordinary life of an ordinary family cannot survive the suspicious scrutiny of millions.

In one . . . completely unverified . . . account of her interrogation, Kate McCann is said to have responded to the accusation that the cadaver dog had picked up the 'scent of death' on her clothes by saying that she had been in contact with six dead patients in the weeks before she came on holiday. My doctor friend doubted this could be true of a part-time GP unless, we joked, she had 'done a Shipman' on them. Then, of course, we had to row back, strenuously, and say that even if something had happened between mother and child, or between father and child, in that apartment, even if the child just fell, then Kate McCann was still the most unfortunate woman you could ever lay eyes on.

And we are obliged to lay eyes on her all the time. This makes harridans of us all.

Rumour and allegation The move from unease, through rumour, to mass murder took no time flat. During the white heat of media allegations against Madeleine's parents, my husband came up the stairs to say that they'd all been wife-swapping . . . that was why the other diners corroborated the McCanns' account of the evening. This, while I was busy measuring the distance from the McCanns' holiday apartment down the road to the church on Google Earth (0.2 miles). I said they couldn't have been wife-swapping, because one of the wives had brought her mother along.

"Hmmmm, " he said.

I checked the route to the open roadworks by the church, past a car park and a walled apartment complex, and I thought how easy it would be to carry my four-year-old son that distance.

I had done that and more in Tenerife, when he decided against walking. Of course he was a live and not a dead weight, but still, he is a big boy.

Too big to fit into the spare-tyre well of a car, as my father pointed out to me later, when it seemed like the whole world was figuring out the best way to kill a child.

"She was only a slip of a thing, " I said.

I did not say that the body might have been made more pliable by decomposition. And I had physically to resist the urge to go out to my own car and open the boot to check (get in there now, sweetheart, and curl up into a ball). Then, as if to pass the blame back where it belonged, I repeated my argument that if there is 88% accurate DNA from partly decomposed bodily fluids found under the carpet of the boot of the hired car, then these people had better fly home quick and get themselves another PR company.

If.

Who needs a cadaver dog when you have me?

In August, the sudden conviction that the McCanns 'did it' swept over our own family holiday in a peculiar hallelujah. Of course they had.

It made a lot more sense to me than their leaving the children to sleep alone.

I realise that I am more afraid of murdering my children than I am of losing them to a random act of abduction. I have an unhealthy trust of strangers. Maybe I should believe in myself more, and in the world less, because despite the fact that I am one of the most dangerous people my children know, I keep them close by me.

I don't let them out of my sight. I shout in the supermarket, from aisle to aisle. I do this not just because some dark and nameless event will overtake them before the checkout, but also because they are not yet competent in the world.

You see? I am the very opposite of the McCanns.

Distancing yourself from the McCanns is a recent but potent form of magic. It keeps our children safe. Disliking the McCanns is an international sport. You might think the comments on the internet are filled with hatred, but hate pulls the object close; what I see instead is dislike . . . an uneasy, unsettled, relentlessly petty emotion. It is not that we blame them . . . if they can be judged, then they can also be forgiven. No, we just dislike them for whatever it is that nags at us. We do not forgive them the stupid stuff, like wearing ribbons, or going jogging the next day, or holding hands on the way into Mass.

I disliked the McCanns earlier than most people (I'm not proud of it). I thought I was angry with them for leaving their children alone. In fact, I was angry at their failure to accept that their daughter was probably dead. I wanted them to grieve, which is to say, to go away. In this, I am as bad as people who complain that "she does not cry".

On 25 May in their first television interview, given to Sky News, Gerry McCann spoke a little about grief, as he talked about the twins.

"We've got to be strong for them, you know, they're here, they do bring you back to earth, and we cannot, you know, grieve one. We did grieve, of course we grieved, but ultimately we need to be in control so that we can influence and help in any way possible, not just Sean and Amelie, but the investigation."

Most of the animosity against the McCanns centres on the figure of Madeleine's beautiful mother. I am otherwise inclined. I find Gerry McCann's need to 'influence the investigation' more provoking than her flat sadness, or the very occasional glimpse of a wounded narcissism that flecks her public appearances. I have never objected to good-looking women. My personal jury is out on the issue of narcissism in general; her daughter's strong relationship with the camera lens causes us a number of emotions, but the last of them is always sorrow and pain.

Guilt and denial. The McCanns feel guilty. They are in denial.

They left their children alone. They cannot accept that their daughter might be dead. Guilt and denial are the emotions we smell off Gerry and Kate McCann, and they madden us.

I, for example, search for interviews with them late at night on YouTube. There is so much rumour; I listen to their words because they are real, because these words actually did happen, one after the other. The focus of my 'dislike' is the language that Gerry McCann uses; his talk of 'information technology' and 'control', his need to 'look forward'.

"Is there a lesson here, do you feel, to other parents?"

"I think that's a very difficult thing to say, because, if you look at it, and we try to rationalise things in our head and, ultimately, what is done is done, and we continually look forward. We have tried to put it into some kind of perspective for ourselves."

He lays a halting and agonised emphasis on the phrase 'what is done is done' and, at three in the morning, all I can hear is Lady Macbeth saying this line after the murder of Duncan, to which her husband replies: "We have scorched the snake, not killed it." Besides, what does he mean? Who did the thing that has been done? It seems a very active and particular word for the more general act of leaving them to go across the complex for dinner.

There are problems of active and passive throughout the McCanns' speech. Perhaps there are cultural factors at play. I have no problem, for example, with Kate McCann's reported cry on the night of 3 May: "They've taken Madeleine." To my Irish ears 'they' seems a common usage, recalling Jackie Kennedy's "I want the world to see what they've done to my Jack, " at Dallas. I am less happy with the line she gives in the interview when she says: "It was during one of my checks that I discovered she'd gone." My first reaction is to say that she didn't just go, my second is to think that, in Ireland, 'she'd gone' might easily describe someone who had slipped into an easy death.

Then I rewind and hear the question, "Tell us how you discovered that Madeleine had gone?" and realise that no one can name this event, no one can describe the empty space on Madeleine McCann's bed.

Perhaps there is a Scottish feel to Gerry McCann's use of 'done'. The word is repeated and re-emphasised when he is asked about how Portuguese police conducted the case, particularly in the first 24 hours. He says: "I think, em, you know, we are not looking at what has been done, and I don't think it helps at this stage to look back at what could and couldn't have been done. . . The time for these lessons to be learned is after the investigation is finished and not now."

Evidence and investigation I am cross with this phrase, 'after the investigation is finished'. Did he mean after they'd packed up their charts and evidence bags and gone home? Surely what they are involved in is a frantic search for a missing child: how can it be finished except by finding her, alive or dead? Why does he not say what he means? Again, presumably because no one can say it: there can be no corpse, killed by them or by anyone else.

Still, the use of the word 'investigation' begins to grate (elsewhere, Kate McCann said that one of the reasons they didn't want to leave Portugal is that they wanted "to stay close to the investigation"). Later in the interview the word changes to the more banal but more outward-looking 'campaign'. "Of course the world has changed in terms of information technology and the speed of response, you know, in terms of the media coming here and us being prepared, em, to some extent to use that to try and influence the campaign, but above all else, it's touched everyone. Everyone."

The sad fact is that this man cannot speak properly about what is happening to himself and his wife, and about what he wants. The language he uses is more appropriate to a corporate executive than to a desperate father. This may be just the way he is made.

This may be all he has of himself to give the world, just now. But we are all used to the idea of corporations lying to us, one way or another . . . it's part of our massparanoia, as indeed are the couple we see on the screen. No wonder, I think, they will not speak about that night.

Then I go to bed and wake up the next day, human again, liking the McCanns.