‘I understand what you’re saying,’ I reply. ‘And I’ve heard of people like the ones you’re describing, internet trolls and what have you, but they are usually threatening or insulting. This letter doesn’t seem like it was written by someone like that. And how could they replicate my daughter’s handwriting?’

PC Kitson sighs and shakes his head.

‘I don’t know, could it be one of your daughter’s school friends?’ he says. ‘In my experience children deal with grief in a variety of ways, some pretty strange.’

‘If that was the case then it would mean a ten-year-old child had snuck out last thing at night to post it. That doesn’t add up.’

‘Didn’t you say the letter was on the mat at nine thirty?’ says Kitson. ‘And you and your friend had been sitting in the front room for quite a while and not heard anything being put through the letter box?’

I nod my head.

‘Well then, it could have been posted at any time during the evening,’ he says. ‘It’s summer. Light nights. Kids are playing out for longer.’

‘Some kids,’ I say, glaring at him.

‘I’m sorry,’ he says, his face flushing. ‘I didn’t mean to be insensitive.’

‘It’s okay,’ I say. ‘I just want to find her.’

‘Mrs Allan,’ he says, getting to his feet, ‘I’m sorry you’ve had to be exposed to this. It’s the last thing a grieving parent should have to deal with.’

I nod my head and slowly stand up, feeling dizzy with the heat. I know he’s never going to help me. I’m on my own.

‘But if any more of these come through, let us know,’ he says, opening the door.

‘I will,’ I say as we step out into the corridor. ‘Oh and could I ask you to let DS Grayling know about the letter too? She’s been working on this case.’

‘DS Grayling’s not here today,’ he says, leading me back along the corridor towards reception. ‘But I’ll let her know what’s happened.’

‘Thank you.’

When we reach the main doors he leans over me to open them. It’s then I see that he is still holding the letter in his hand.

‘May I please keep that?’ I say, turning to face him.

He looks down at the letter and frowns.

‘I’m not sure if that’s a good idea.’

‘Please,’ I say. ‘I want to hold on to it.’

He looks at me with pity and who can blame him? Here I am standing in a pair of old pyjamas, insisting my dead daughter is alive somewhere. Still, despite what he thinks, I need that letter.

‘Please?’ I say.

He relents and hands me the letter.

‘Thank you,’ I say, then slip it into my coat pocket.