‘So until your mother phoned, you had no inkling of any problem?’ asks Mr Wright.

I feel the familiar, nauseating, wave of guilt. ‘No. Nothing I took any notice of.’

I went first class, it was the only seat they had left. As we flew through cloud limbo land I imagined telling you off for putting me through this. I made you promise not to pull a stunt like this again. I reminded you that you were going to be a mother soon and it was about time you started behaving like an adult.

‘“Older sister” doesn’t need to be a job title, Bee.’

What had I been lecturing you about at the time? It could have been one of so many things; the point is that I’ve always viewed being an older sister as a job, one that I am ideally suited for. And as I flew to find you, because I would find you (looking after you is an essential part of my job description), I was comforted by the familiar scenario of being the superior, mature, older sister telling off the flighty, irresponsible young girl who should know better by now.

The plane started to descend towards Heathrow. West London sprawled beneath us, thinly disguised with snow. The seat-belt light came on and I made deals with God: I’d do anything if you were found safe. I’d have made a deal with the devil if he’d been offering.

As the plane bumped clumsily onto the tarmac, my fantasy annoyance crumbled into sickening anxiety. God became the hero in a children’s fairy story. My powers as an older sister dwindled to still impotency. I remembered viscerally Leo’s death. Grief like swallowed offal made me wretch. I couldn’t lose you too.