My job, as Night Duty Officer, is to sit tight and answer the phone. In the unlikely event that it rings, I have a list of numbers I can call. Most of them ring through to duty officers in other departments, but one of them calls through to a special Army barracks in Hereford, another goes straight to SHAPE in Brussels-that’s NATO’s European theatre command HQ-and a third dials direct to the COBRA briefing room in Downing Street. Nobody in the Laundry has ever had to get the Prime Minister out of bed in the small hours, but there’s always a first time: more importantly, it’s the NDO’s job to make that call if a sufficiency of shit hits the fan on his watch.

I’ve also got a slim folder (labelled TOP SECRET and protected by disturbing wards that flicker across the cover like electrified floaters in the corners of my vision) that contains a typed list of codewords relating to secret operations. It doesn’t say what the operations are, but it lists the supervisors associated with them-the people to call if one of the agents hits the panic button.

I’ve got an office to hang out in. An office with a bunk bed like something out of a fifties Carry On film about conscript life in the army, a chimney for the wind to whistle down (the better to keep me awake), a desk with an ancient computer terminal (shoved onto the floor to make room for my laptop), and a kettle (there’s a bathroom next door with a sink, a toilet, and a shower that delivers an anemic trickle of tepid water). There’s even a portable black-and-white TV with a cheap Freeview receiver (this is the first year since they discontinued analog broadcasting) in case I feel compelled to watch reruns of The Two Ronnies.

All the modern conveniences, in other words…

The Office Party is scheduled to take place on Wednesday afternoon, from 1 p.m. to 5 p.m. sharp.

As civil servants, however irregular, we’re not paid enough to compete with the bankers and corporate Tarquins and Jocastas who fill most of the office blocks in this part of the city; even in these straitened times they can afford to drop a couple of hundred notes per head on bubbly. So we don’t get a posh restaurant outing: instead we have to tart up the staff canteen with some added tinsel, fake snow spray on the windows, and a molting pine tree in a pot by the fire exit.

Pinky and Brains kindly installed their home stereo-homemade, not homesized-in the number two lecture theatre, for the obligatory dance; Elinor and Beth (with a nod and a wink from Oversight) hit on an outside caterer for the sort of comestibles essential to a party and unheard-of in a civil service canteen (which could manage cupcakes and sherry trifle if push came to shove, but whose idea of pizza or curry is ghastly beyond belief).

There’s a Dunkirk spirit to the whole affair: with the new government in the driving seat, wielding the chainsaw of budget cuts, there’s not a lot of luxury to go round. But we’re good at make-do-and-mend in this department-it’s bred in our bureaucratic bones-and with the aid of a five hundred quid ents budget (to cover the hundred odd folks who work here), we make it work.

There is a humdrum ritual for an office Christmas party anywhere in England. The morning beforehand, work takes on a lackadaisical feel. Meetings are truncated by 11 a.m.; agendas updated, email filters set to vacation. Some folks-the few, the lucky-begin to clear their desk drawers, for they know they shall not be coming back to work until the new year. A wilted air of festivity wafts through the corridors of power, like a slightly moist crêpe banner.

“Bob?” I look up from my Minesweeper session: it’s Andy, my sometime manager, leaning in the doorway. “You coming to lunch?”

I stretch, then mouse over to the screen lock. “Is it that time already?” I don’t work for Andy these days, but he seems to take a proprietorial interest in how I’m doing.

“Yes.” His head bounces up and down. He looks slightly guilty, like a schoolboy whose been caught with his hands in the sweets jar once too often. “Is Mo…?”

“She’s off-site today.” I stand up. Actually she’s over in Research and Development, quaffing port with the double-domes, dammit-an altogether more civilized session than this one. “We were planning on meeting up later.”

“Well, come on then. Wouldn’t want to miss the decent seats for the floor show, would we?”

“Floor show?” I close the door behind us.

“Yes, we have a visitor from Forecasting Ops. I got the email a couple of days ago. One Dr. Kringle has condescended to descend and give us some sort of pep talk about the year ahead.”

“Kringle?” My cheek twitches. The name’s unfamiliar. “From Forecasting Ops? Who are they…” I’ve heard rumors about them, but nothing concrete: it’s probably one of those vague backwaters beavering away in isolation. Why on earth would they want to send someone to talk to us now?

“Yes, exactly.” Andy spares me a sidelong glance. “Don’t ask me, all I know is what I found in my inbox. Mail from HR, let him give a little motivational pep talk at the party. Don’t worry,” he adds quietly, “it’ll all work out for the best in the end. You’ll see. Just sit tight and bite your tongue.” I get it. Andy is wearing his bearer-of-bad-news face while steering me towards the junior officer’s bench. Something is about to come down the chute, and all the Christmas cheer in the world isn’t going to cover up the stench of manure. As a management-grade employee-albeit a junior one-I’m required to show solidarity. Hence being tipped the nod and a wink.

I begin to wonder what it can possibly be.

The Duty Officer’s room is upstairs, just under the gently pitched roof of the New Annexe. There’s a wired-shut skylight, and the wind howls and gibbers overhead: occasionally there’s a sound like gravel on concrete as an errant gust flings a cupful of freezing cold water at the glass, followed by a hollow booming noise from the chimney. The chimney is indeed warm, but it’s cooling fast: I guess they’ve shut down the incinerator over the holiday period. It’s just past eleven at night, and there’s no way in hell I’m going to be able to sleep while the storm is blowing.

When the holiday falls on a weekend day (as Boxing Day does this year) everyone gets a day off in lieu at the beginning of the following week except the Night Duty Officer, who is in it for up to four days at triple pay-as long as he doesn’t go mad with boredom first.

I’ve been on duty for six hours and I’ve already caught up on my work email-at least, I’ve replied to everything that needs replying to, and am well into ignoring all the Powerpoints that need ignoring-and gotten bored with gaming. The TV’s on in the background, but it’s the same-old family-friendly fare. I don’t want to start on the two fat novels I’ve stockpiled for the weekend too early, so there’s only one thing to do. I abandon my cup of tea, pick up my torch, iPhone and warrant card, and tip-toe forth to poke my nose where it doesn’t belong.

’Twas the night before Christmas, the office was closed,

The transom was shut, the staff home in repose;

The stockings were hung by the chimney with care,

But St. Nicholas won’t be coming because this is a Designated National Security Site within the meaning of Para 4.12 of Section 3 of the Official Secrets Act (Amended) and unauthorised intrusion on such a site is an arrestable offense…

Had enough of my poetry yet? That’s why they pay me to fight demons instead.

One of the perks of being Night Duty Officer is that I can poke my nose anywhere I like-after all, I’m responsible for the security of the building. In fact, I can go into places where I’d normally get my nasal appendage chopped right off if I had the temerity to sniff around without authorization. I can look inside Angleton’s office, tip-toe between the dangerously active canopic jars and warded optical workbenches of Field Service, walk the thickly carpeted, dusty corridors of Mahogany Row, and pester the night-shift zombies (sorry: of course I meant to say, Residual Human Resources) in the basement. In fact, I’m pretty much encouraged to keep an eye on things, just as long as I stay within range of the Duty Officer’s Phone.