As long as an ambulance is en route, I can talk this woman through the rest of our well-practised protocol. Tabby’s class teacher, Miss Conway, has far more experience of dealing with her condition, but I’m all too aware that she’s responsible for twenty-nine other kids, too. ‘Listen to me. Get her to the school office as quickly as you can. Mrs Hopkins knows the score. Put Tabs back on, can you?’

As I talk, I push back my chair and get on my knees, pulling my tote bag from beneath my desk before reaching further back for Tabby’s A&E backpack. I have one at home and one at the office, both permanently packed and ready to go for whenever we have a spontaneous visit to Accident & Emergency. They contain the bare minimum: books and colouring paraphernalia; healthy snacks; a phone charger; toothbrushes; PJs for Tabs and clean underwear for both of us in case they end up admitting her overnight, plus the obligatory earplugs. There is nowhere on the planet less conducive to a night’s sleep than a paediatrics ward in a busy London hospital.

We’re old hands at this routine by now.

‘Yes. Okay, I’ll—hang on.’ The TA sounds even more out of breath than the little girl currently suffering from oxygen deprivation.

My daughter’s face reappears, and I force my expression into a smile I hope is confident, competent, and reassuring in equal measure. ‘Hi again, my love. The ambulance is going to come and get you, and Miss, er, Lewis is going to go with you. But you need to get to the office so Mrs Hopkins can take your sats, okay? Do you think you can walk there? Are you feeling dizzy?’

I already know the answer to that. Her deathly pale complexion is evidence enough that she’ll be feeling lightheaded, but she nods. ‘Yeah, but I can walk.’ Her voice is so quiet.

‘That’s my brave girl.’ I kick off my heels and push my feet one by one into a pair of trainers, slamming my laptop shut as I do and then shoving it into the tote.

‘Will you come in the ambulance too, Mummy?’

‘I can’t, angel. I’m at work. I’ll have to get the tube straight to the hospital and meet you there. But I’ll stay on the line until the paramedics turn up, I promise.’

No way in hell am I risking going underground until I know Tabby’s in the hands of professionals. I tug my long hair over one shoulder so I can toss both bags over the other. ‘Hang on a sec,’ I tell my daughter, and I clamp the phone to my boob for a little privacy. My boss, Dean, is preemptively glaring at me.

‘Tabby needs to go to hospital. I’m sorry. I’ll log in when I get there.’