The man behind me is standing close enough to moisten the skin on my neck with his breath. I move my feet forward an inch and press myself into a grey overcoat that smells of wet dog. It feels as if it hasn’t stopped raining since the start of November, and a light steam rises from the hot bodies jammed against each other. A briefcase jabs into my thigh. As the train judders around a corner I’m held upright by the weight of people surrounding me, one unwilling hand against the grey overcoat for temporary support. At Tower Hill the carriage spits out a dozen commuters and swallows two dozen more, all hell-bent on getting home for the weekend.

‘Use the whole carriage!’ comes the announcement.

Nobody moves.

The grey overcoat has gone, and I’ve shuffled into its place, preferable because I can now reach the handrail, and because I no longer have a stranger’s DNA on my neck. My handbag has swung round behind my body, and I tug it in front of me. Two Japanese tourists are wearing gigantic rucksacks on their chests, taking up the space of another two people. A woman across the carriage sees me looking at them; she catches my eye and grimaces in solidarity. I accept the eye contact fleetingly, then look down at my feet. The shoes around me vary: the men’s are large and shiny, beneath pinstriped hems; the women’s heeled and colourful, toes crammed into impossible points. Amongst the legs I see a pair of sleek stockings; opaque black nylon ending in stark white trainers. The owner is hidden but I imagine her to be in her twenties, a pair of vertiginous office heels stashed in a capacious handbag, or in a drawer at work.

I’ve never worn heels during the day. I was barely out of my Clark’s lace-ups when I fell pregnant with Justin, and there was no place for heels on a Tesco checkout, or coaxing a toddler up the high street. Now I’m old enough to know better. An hour on the train on the way into work: another hour on the way home. Tripping up broken escalators. Run over by buggies and bikes. And for what? For eight hours behind a desk. I’ll save my heels for high days and holidays. I wear a self-imposed uniform of black trousers and an array of stretchy tops that don’t need ironing, and are just smart enough to pass as office-wear; with a cardigan kept in my bottom drawer for busy days when the door’s forever opening and the heat disappears with every prospective client.

The train stops and I push my way on to the platform. I take the Overground from here, and although it’s often as busy, I prefer it. Being underground makes me feel uneasy; unable to breathe, even though I know it’s all in my head. I dream of working somewhere close enough to walk to, but it’s never going to happen: the only jobs worth taking are in zone one; the only affordable mortgages in zone four.

I have to wait for my train and at the rack by the ticket machine I pick up a copy of the London Gazette, its headlines appropriately grim for today’s date: Friday 13 November. The police have foiled another terrorism plot: the front three pages are rammed with images of explosives they’ve seized from a flat in North London. I flick through photos of bearded men, and move to find the crack in the tarmac beneath the platform sign, where the carriage door will open. My careful positioning means I can slide into my favourite spot before the carriage fills up; on the end of the row, where I can lean against the glass barrier. The rest of the carriage fills quickly, and I glance at the people still standing, guiltily relieved to see no one old, or obviously pregnant. Despite the flat shoes, my feet ache, thanks to standing by the filing cabinets for most of the day. I’m not supposed to do the filing. There’s a girl who comes in to photocopy property details and keep the cabinets in order, but she’s in Mallorca for a fortnight and from what I saw today she can’t have done any filing for weeks. I found residential mixed up with commercial, and lettings muddled up with sales, and I made the mistake of saying so.

‘You’d better sort it out, then, Zoe,’ Graham said. So instead of booking viewings I stood in the draughty corridor outside Graham’s office, wishing I hadn’t opened my mouth. Hallow & Reed isn’t a bad place to work. I used to do one day a week doing the books, then the office manager went on maternity leave and Graham asked me to fill in. I was a bookkeeper, not a PA, but the money was decent and I’d lost a couple of clients, so I jumped at the chance. Three years later, I’m still there.

By the time we reach Canada Water the carriage has thinned out and the only people standing are there by choice. The man sitting next to me has his legs so wide apart I have to angle mine away, and when I look at the row of passengers opposite I see two other men doing the same. Is it a conscious thing? Or some innate need to make themselves bigger than everyone else? The woman immediately in front of me moves her shopping bag and I hear the unmistakable clink of a wine bottle. I hope Simon has thought to put one in the fridge: it’s been a long week and right now all I want to do is curl up on the sofa and watch telly.

A few pages into the London Gazette some former X Factor finalist is complaining about the ‘pressures of fame’, and there’s a debate on privacy laws that covers the best part of a page. I’m reading without taking in the words: looking at the pictures and scanning the headlines so I don’t feel completely out of the loop. I can’t remember the last time I actually read a whole newspaper, or sat down to watch the news from start to finish. It’s always snatches of Sky News while I’m eating breakfast, or the headlines read over someone’s shoulder on the way in to work.

The train stops between Sydenham and Crystal Palace. I hear a frustrated sigh from further up the carriage but don’t bother looking to see who it’s from. It’s already dark and when I glance at the windows all I see is my own face looking back at me; even paler than it is in real life, and distorted by rain. I take off my glasses and rub at the dents they leave either side of my nose. We hear the crackle of an announcement but it’s so muffled and heavily accented there’s no telling what it was about. It could have been anything from signal failure to a body on the line.

I hope it’s not a body. I think of my glass of wine, and Simon rubbing my feet on the sofa, then feel guilty that my first thought is about my own comfort, not the desperation of some poor suicidal soul. I’m sure it’s not a body. Bodies are for Monday mornings, not Friday evenings, when work is a blissful three days away.

There’s a creaking noise and then silence. Whatever the delay is, it’s going to be a while.

‘That’s not a good sign,’ the man next to me says.

‘Hmm,’ I say non-committally. I carry on turning the pages of my newspaper, but I’m not interested in sport and now it’s mostly adverts and theatre reviews. I won’t be home till after seven at this rate: we’ll have to have something easy for tea, rather than the baked chicken I’d planned. Simon cooks during the week, and I do Friday evening and the weekend. He’d do that too, if I asked him, but I couldn’t have that. I couldn’t have him cooking for us – for my children – every night. Maybe I’ll pick up a takeaway.

I skip over the business section and look at the crossword, but I don’t have a pen with me. So I read the adverts, thinking I might see a job for Katie – or me, come to that, although I know I’ll never leave Hallow & Reed. It pays well and I know what I’m doing, now, and if it wasn’t for my boss it would be perfect. The customers are nice, for the most part. They’re generally start-ups, looking for office space; or businesses that have done well, ready for a bigger place. We don’t do much residential, but the flats above the shops work for the first-time buyers and the downsizers. I meet a fair number of recently separateds. Sometimes, if I feel like it, I tell them I know what they’re going through.

‘Did it all turn out okay?’ the women always ask.

‘Best thing I ever did,’ I say confidently. It’s what they want to hear.

I don’t find any jobs for a nineteen-year-old wannabe actress, but I turn down the corner on a page with an advert for an office manager. It doesn’t hurt to know what’s out there. For a second I imagine walking into Graham Hallow’s office and handing in my notice, telling him I won’t put up with being spoken to like I’m dirt on the sole of his shoe. Then I look at the salary printed under the office manager position, and remember how long it’s taken me to claw my way up to something I can actually live on. Better the devil you know, isn’t that what they say?

The final pages of the Gazette are all compensation claims and finances. I studiously avoid the ads for loans – at those interest rates you’d have to be mad or desperate – and glance at the bottom of the page, where the chatlines are advertised.

I wrinkle my nose more at the exorbitant price per text than the services offered. Who am I to judge what other people do? I’m about to turn the page, resigned to reading about last night’s footie, when I see the advert below ‘Angel’s’.

For a second I think my eyes must be tired: I blink hard but it doesn’t change anything.

I’m so absorbed in what I’m looking at that I don’t notice the train start up again. It sets off suddenly and I jerk to one side, putting my hand out automatically and making contact with my neighbour’s thigh.

‘Sorry!’

‘It’s fine – don’t worry.’ He smiles and I make myself return it. But my heart is thumping and I stare at the advert. It bears the same warning about call charges as the other boxed adverts, and a 0809 number at the top of the ad. A web address reads www.findtheone.com. But it’s the photo I’m looking at. It’s cropped close to the face, but you can clearly see blonde hair and a glimpse of a black strappy top. Older than the other women pimping their wares, but such a grainy photo it would be hard to give a precise age.

Except I know how old she is. I know she’s forty.

Because the woman in the advert is me.