Serena Mackesy In my week

If we ever went to war with the States, all we'd have to do to spot their spies would be to get everyone to read out the word `Leominster'

Tower Hill tube station. Not a place to go if you've a heavy load because tourists have a peculiar talent for stopping in large, tight-knit knots wherever there's a bottle-neck. Getting through the gates is an ordeal in itself, dodging the flail of Nikes as another group of blue-rinses gasp at the technological demands of putting a ticket in a slot.

My duffel bag of press releases, my urban rucksack of communications equipment and my six Tesco carrier bags of foodie junk take five minutes to get from caramel peanut seller to District Line platform. It suppurates with bum-bags, Crimplene trousers and pocket maps. Among the new laws which bit the dust when I lost my deposit on Thursday was one saying that places of historic interest could not open or close their doors during rush-hour. This wouldn't solve the American problem, as they will always rush back to their B&Bs for supper at six, but at least there would be elbow room to put the odd snarly French schoolchild over one's knee and give it the spanking it so richly deserves.

The Westbound platform splits at Tower Hill. On one side, trains from the East End come through. On the other, trains from Wimbledon end their run and idle for a bit, while, if you're lucky, an old bloke in orange overalls plods through and makes room for the next lot of burger wrappers. But the point is this: you can always sit down on one of these trains, even when the entire staff of BZW are carting their six-figure weekly bonuses home by briefcase. You may get home a bit later, but that little single seat is yours for the taking.

I arrange my bags around my feet to guard against the power-dressing PAs who stalk the District Line looking for bohos to transfix with their spike heels, and settle down with my book on criminology. People run along the platform, jump onto my train, see that the arrow on the NEXT TRAIN OUT sign is pointing to the other side, jump off again. The carriage gradually fills with other Tube bores.

"Excuse me." I look up. Two men loom over me: sandy moustaches, fringe- cut fair hair, belted Mackintoshes. I assume they're gay, then remember that just because some gay men affect the preppie look doesn't mean that all preppies are gay. "Mmm?" "Does this train go to Glau-sesster Road?" I nod. "Thank you," he says. I remember the arrow. "It's not the first one out, though." "Oh," he says, "How come all these people are waiting, then? Are they stupid?" I shake my head. Hell, I don't mind strangers calling me stupid. "You can get a seat on this train." "Wad time's it leave?" "I don't know. When it goes, I guess."

He considers this, then sits down. I find myself lost in contemplation of the brilliant way the British have designed their names to fox outsiders. Having a surname designed to discomfit the filthy Sassenach, the subject is dear to my heart. If we ever went to war with the States, all we'd have to do to spot their spies would be to get everyone to read out the word "Leominster". My mate got asked for directions for Lugabarruga the other day. Turned out it was spelt Loughborough.

Then I realise the Yanks are discussing me. "Wad she say?" says friend of moustache. "She said `Mwaah mwaah mwaah'," says moustache. Friend laughs. He has no facial hair, but the remains of an adolescent hormone imbalance are etched into his cheeks. "Mwaah mwaah," he says. "Gaad," says moustache, "Wad kinda country is this anyway? These people don't even know when their trains run."

I think about pointing out that if he wants a London Underground employee he should find someone in uniform. My cheeks are burning. A train pulls in on the other platform. The doors open and the sardines of rush-hour tumble out. My companions look at each other, then at me, as though I am playing a prank on them. The train moves off. The arrow still points away.

"When she say it was leaving?" says friend. "I couldn't understand her," says moustache. "She just went `mwaah mwaah'." "Why don't you ask her again?" "Don't be stupid. There is no point asking the English anything. They never know."

Excuse me matey, I think, but still don't say because I'm too well trained, I'm probably less English than you are. I've got an English great-grandmother, but the rest is pure Celt. Friend leans toward me, shouts down the train. "Say," he says, "When we gonna be moving?" "I don't know. I'm sorry." They look at each other, burst out laughing and go "mwaah mwaah" a few more times.

A Circle line train arrives on the other side, empties, pulls out. The arrow flicks towards me. The gits have started in on our train system and how stupid we are not to have razed our medieval street plan to make grids like New York has. Then they start going "mwaah" again, purpling with their own wit.

Sod this, I think. I look up the carriage, attract their attention. "Excuse me. The next train's going from the other platform too." They leap up and sprint from the carriage. A couple of seconds later, the doors slide shut. I smile sweetly and wave as we pull out of the station.