‘But what I don’t understand,’ I say slowly, carefully, ‘is how she ended up so alone. She died – and I still don’t even know how – but even worse is that she lay in her flat for so long. That’s the bit I’m trying to understand. I mean, I remember her as outgoing too, but there must have been some kind of difficulty she had, some kind of falling out, some kind of rupture with her friends? Her family too … Marianne, she’d removed all her contacts from her phone. Or perhaps she was shy really, or she didn’t trust people, or …’

But Marianne is shaking her head. ‘No, no … That’s all wrong. She wasn’t like that at all.’ She takes another sip of her water. ‘She was close to her parents, talked about them a lot. Don’t you remember that photograph on her desk? And she had lots of friends, a whole London set. She was very, very popular. But kind as well, generous. Not the sort to fall out with people. She was always happy, always having fun. Going to parties, booking her next holiday. Between her temp contracts, she always seemed to be jetting off abroad. Outside the office, really she had quite a glamorous life.’

Glamorous? I try to grasp the picture Marianne is painting, and hold it alongside what I saw, what I know. That tiny bedsit, covered in dust, the rent unpaid, her door silted up with post. The two images seem whole worlds apart. And yet, haven’t I always trusted Marianne’s judgement? How many times have I known her to be right? I reach out and take another gulp of my own water, buying time to think of what to say next.

‘So then … when did you last see her?’ I ask. ‘She died … she died months and months ago so, I mean, did she just stop coming in to work?’

Marianne shakes her head again, almost violently. ‘Oh no, she wouldn’t do that. She wouldn’t just abandon us like that. She got head-hunted. That’s what happened.’

‘Head-hunted?’

‘It must have happened quite suddenly. I didn’t even realize she was going, but after all, she didn’t have a notice to serve. I had a week off, you see, and when I came back, she’d cleared her desk. The others told me that she got recruited by a big firm, a legal firm I think it was.’

‘A legal firm? So when was the last time you saw her?’

Marianne frowns, thinking carefully. ‘It would have been … last January. The very end of the month. I didn’t get a chance to say goodbye to her. When I came back from leave, she was already gone.’

I try to fit the pieces together. Sarah moved into the flat last February. But a big legal firm was nowhere on her forms.