‘Yes. That’s why I said, “Can you put me through?” ’ I can’t resist adding. Think for yourself, dork. Don’t just stick to the script, because every time you do that, every time one of your colleagues does it, it’s five seconds of my life wasted.

Even if someone isn’t trying to kill me, I still haven’t got any life to spare. I try to find this funny and fail.

The next voice I hear is a woman’s. She gives me the good-morning-Seddon-Hall spiel that I’ve heard several times before. I ask her to check if a man called Mark Bretherick stayed at Seddon Hall between Friday, 2 June and Friday, 9 June 2006. ‘He was in suite number eleven for the first two nights, then in suite fifteen.’ I can picture both rooms clearly, on the top floor of the courtyard bit, on the galleried landing.

The pause before she speaks suggests she might have watched the news lately. ‘Could I ask your name, please?’

‘Sally Thorning. I was a guest at the hotel at the same time.’

‘Do you mind me asking why you need this information?’

‘I just need to check something,’ I tell her.

‘I’m afraid we don’t normally-’

‘Look, forget Mark Bretherick,’ I cut her off. ‘That probably wasn’t his name. There was a man who stayed at Seddon Hall from the second to the ninth of June last year and I need to know who he was. He booked suite eleven for the whole week, but then there was a problem with the hot-’

‘I’m sorry, madam,’ the soft-voiced receptionist interrupts me. I can hear her computer whirring; she’s probably looking at his name on her screen right now. ‘I don’t mean to be unhelpful, but we can’t give out guests’ names without a good reason.’

‘I’ve got a good reason,’ I tell her. ‘Whoever that man was, I spent the week with him. He told me he was Mark Bretherick, but I don’t think he was. And, for reasons that I can’t go into because of my own confidentiality policy, I really need to know his name. Urgently. So, if you could check your records…’

‘Madam, I’m really sorry-I’m afraid it’s unlikely that we’ve kept records from that far back.’

‘Yeah, right. Course it is.’

I slam down the phone. So much for sweet-talking. Was I too honest, or not honest enough? Or did I sound like a bossy cow? Nick says I sometimes ask questions in a way that makes people pray they won’t know the answer.

Last night-because I had to do something-I waited until Nick went to bed and wrote a letter to the police about the Brethericks. It contained almost no information, only that the man identified as Mark Bretherick on the news might be someone else. On my way into work this morning I stopped at Spilling Post Office and put it in the police postbox. By now someone might have read it.

They’ll think I’m a crank. I told them the bare minimum. Anybody could have written what I wrote, to get attention or cause trouble-a drunk teenager, a bored pensioner, anyone. They’ll put me straight in the Wearside Jack category.

I think about what I told the Seddon Hall receptionist: whoever that man was, I spent a week with him. I could have written that in my letter to the police without giving away my identity. Why the hell didn’t I? The more detailed my account, the more likely they would have been to believe me. If I explained everything, how and why it happened… Suddenly I feel a burning need to share the full truth with somebody. Even if it’s only the police, even anonymously. For over a year I’ve kept it completely secret, telling the story to myself but no one else.

I highlight the draft of my salt-marsh habitats article and delete it, leaving only the heading in case someone looks over my shoulder. Then I start to type.

7 August 2007

To whom it may concern

I have already written to you once about the Brethericks. I posted my first letter this morning at about eight thirty, on my way to work. Like this one, it was anonymous. I am writing again because, after posting my last attempt, I realised that it would be easy for you to dismiss me as a time-waster.

I can’t tell you my name for reasons that will become clear. I am female, thirty-eight, married and a mother. I work full-time, and the work I do is professional. I am university educated and have a PhD. (I’m saying this because I can’t help thinking it will make you take me more seriously, so I suppose that makes me a snob too.)

As I said in my last letter, I have reason to believe that the Mark Bretherick I saw on the news last night might not be the real Mark Bretherick. This story may seem irrelevant at first but it isn’t so please bear with me.

In December 2005, my boss asked me if I could go on a work trip abroad, for the week of Friday, 2 June to Friday, 9 June 2006. At that time my children were very young and I was working full-time, juggling several different projects and not getting much sleep. Every day felt like a struggle. I told my boss I didn’t think I’d be able to do it. Since having my second child, I hadn’t been away from home for more than one night at a time. To go away for a whole week didn’t seem fair on my husband and the children, and I felt utterly drained when I imagined getting home afterwards and having to clear up the mess that would have accumulated in my absence. It simply didn’t seem worth it. I felt slightly disappointed at having to turn down the work because it sounded like an interesting project, but I barely gave it a thought because I was so sure it was out of the question.

I told my husband later, expecting him to say, ‘Yeah, there’s no way you could have gone,’ but he didn’t. He looked at me as if I was mad and asked why I’d said no. ‘It sounds like the opportunity of a lifetime. If anyone asked me, I’d go like a shot,’ he said.

‘I can’t. It’s impossible,’ I told him, thinking he must have forgotten we had very young children.

‘Why not? I’ll be here. We’ll manage fine. I might not stay up till midnight every night ironing socks and hankies like you do, but who cares?’

‘I can’t,’ I said. ‘If I go away for a week, it’ll take me two weeks to get on top of everything once I get back.’

‘You mean at work?’ he said.

‘And at home,’ I said. ‘And the kids’ll really miss me.’

‘They’ll be absolutely fine. We’ll have fun. I’ll let them eat chocolate and go to bed late. Look, I can’t look after the kids and keep the house tidy,’ he said, (he could, of course, but he genuinely believes that he can’t) ‘but we can hire some help.’ He mentioned the name of a woman who babysat for us regularly.

As he outlined a possible plan-and I can remember this as vividly as if it happened yesterday-a weird feeling started to grow inside me. At the risk of sounding melodramatic, it felt like some kind of explosion or revelation: I could go. It was possible. My husband was right, the children would be absolutely fine. And I could ring them every morning and every evening, so that they could hear my voice and I could reassure them that I was coming back soon.

Whoever you are that’s reading this: I’m sorry to make it so personal. But if I don’t tell you all this, the rest won’t make sense. It’s not a justification, just an explanation.

A week away, I thought. A whole week. Seven unbroken nights. I could catch up on my sleep. At that point my husband and I were getting up three or four times a night, and each time we might be up for an hour or more, trying to settle a wakeful child. And we were both working full-time as well. It didn’t seem to bother my husband. ‘What’s the worst that can happen?’ he used to say. ‘We’ll be tired, that’s all. It’s not the end of the world.’ (My husband is the sort of person who would say that even if he bumped into someone who was holding a large nuclear bomb and wearing a name-badge that said ‘Nostradamus’.)

I rang my boss and told him I could go after all. I hired the babysitter that my husband had mentioned, and within a couple of days my trip was arranged. I would be staying in a five-star hotel in a country I’d never been to before. I started to fantasise about the trip. All the work stuff would happen during the day, leaving my evenings free. I could have long, hot baths and lovely room service dinners that I wouldn’t have to cook myself. I could go to bed at nine thirty and sleep until seven the next morning-that was the most alluring prospect of all. I’d assumed, without even realising it, that my relationship with proper sleep was over for good.