Andy McNab: Zero hour

I fished in my pocket for the season ticket.

He shooed it away. 'You'll be needing it for next time.'

This was the third time this had happened. 'How much do these things cost?'

'Enough to make my eyes water.'

'Another burden on the bleeding taxpayer.'

'When was the last time you paid tax?' Julian flashed his perfect white teeth. 'Come to that, when was the first time?'

I gave him a 500-watt grin, even though I suddenly had a head full of pain. I palmed two Smarties and swallowed them with a gulp of Pret A Manger's frothiest.

We both stared out over the pitch.

'I've been giving that job a bit of thought.'

Julian glanced behind us. People had started to fill the nearby seats but there was nobody within earshot. His eyebrow arched towards his immaculately sculpted hairline. 'What about Granny's nest egg?'

'She always wanted me to work for a living…'

Jules pulled out his BlackBerry and hit the secure speech icon before dialling. That was a good sign. His spare hand covered the mouthpiece like he thought I'd added lip-reading to my CV.

He closed down and put it back in his pocket. 'OK, you're on. But you'll need to give me a lift in that penis extension of yours.' Jules got to his feet. 'We have an audience with the top man. He'll meet us in three hours. The Blues will have to win without us.'

'Not a chance. West Ham will kick the shit out of them. Three-nil, I reckon.'

GCHQ Cheltenham 17.23 hrs I came off the M5 at junction eleven and followed the A40 east towards Cheltenham. Just before the town, I turned off at a roundabout. Jules switched the radio to medium wave to tune into Talksport.

They were waffling about football and, of course, I'd been way off the mark. Chelsea had won 4-1.

We pulled onto Hubble Road. GCHQ had been the most secretive of Britain's three intelligence services since way back, and I always reckoned they chose this location on the edge of a spa town in rural Gloucestershire just to add to the mystique. While MI5 and MI6 gathered human intelligence, GCHQ's main mission was soaking up the signals equivalent, via the interception of phone calls, faxes, emails or any other electronic means. They monitored the airwaves for any vital snippet that might stop a terrorist attack in the UK or help the military in Afghanistan. They were also tasked with protecting the government's communications against attack by enemy code-breakers.

This was Boffin Central, where some of the world's most powerful computers played tunes for people with brains the size of a planet. I smiled to myself as I remembered the TV commercial for Tefal. A group of white-coated boffins with extra large heads hovered over a new kettle or iron, making sure it was perfect for the likes of me. They must have filmed it right here.

The man we were going to meet was Julian's new boss. The whole of the British intelligence community's new boss, by the sound of it. Tresillian had been made uber-chief of all three services – MI5, MI6 and GCHQ – a position that had only just been created.

'There's a thread of continuity at last. If GCHQ picks up a whisper, he can give the order for SIS to take immediate action. None of the old red tape.'

'Or the old checks and balances?'

I slowed. There was a barrier across the road ahead, manned by two guys in uniform. The first layer of security. Jules flashed his pass and we were waved through.

'Seriously new broom. Actually – new broom, old handle. His family go back to before the Domesday Book.'

I nodded. The most powerful people the world over are the ones we'll never hear about. Like those who are so rich they make sure they never feature on Forbes' List or the Sunday Times Richest.

'That's nice for him. But is he any good?'

'Shit-fucking-hot, if he says so himself.'

I was so surprised I took my eye off the road. I'd never heard him swear.

He directed me to the car park at the front of the huge steel building. Everyone called it the Doughnut. Viewed from above, that was exactly what it looked like.

I drew level with a black BMW 5 that was three up.

Julian nodded. 'Tresillian's already here.'

'Hope he's got the kettle on.'

The driver was still behind the wheel, in weekend clothes. The engine was running. He was watching a DVD on a windscreen-mounted player. The two in the back were in suits that looked just a little too small for them. They were waiting for their principal to finish his meeting with us so they could take him home.

The driver's window came down and Jules said hello.

As I got out, I recognized a scene from The Transporter. I nodded. 'Great movie.'

I got no reply. The window slid back up.

A sign by the main doors said cameras, mobile phones and recording equipment or similar electronic devices were forbidden in the main building.

Jules handed the woman at Reception some ID that looked like a credit card and she swiped it through a reader. 'Good evening, Mr Drogba.' She passed him a form to sign, checked it, and passed me a red badge. 'If you could hand that back in when you leave, Mr Lampard?' She didn't bat an eyelid.

We hadn't even got past the main reception area before we hit another layer of security. This time it included the electronic equivalent of a full body search. We carried on and followed a circular walkway that ran inside the building. Everyone called it the Street. It felt a bit like being in an airport terminal, with open-plan offices leading off both sides. Glass cases displayed exhibits from GCHQ's history, including the radio set used by the Portland spy ring to send messages back to Russia in the fifties and sixties.

'I don't know what the layout was before, Nick, but now the linguists and analysts work on the upper floor. They've had to squash up to accommodate CSOC.'

The cross-governmental Cyber Security Operations Centre was another new one on me. It had recently been set up to deal with any threat Britain might face from the Internet – and to carry out some cyber attacks of its own.

All the guys on the upper floor spent their time studying intelligence on everything from terrorism and nuclear proliferation to serious organized crime and counter-espionage. It was no place for the likes of me. Neither was the basement. I remembered the huge halls with endless rows of blinking computers. In all there were about ten thousand square metres of the things. They generated so much heat they needed a cooling system that used a lot of local water. During the floods in 2007, the mains were cut and special supplies had to be tankered in.

We passed something I didn't remember from past visits: a small memorial honouring the number of GCHQ staff who had died in service. More had been dropped in Afghanistan in the past few years than anywhere else.

I followed Jules from the bright, fluorescent corridor into a room where the only light seemed to come from the glow of plasma screens mounted on a walnut-veneered wall.

As I closed the door behind me, the hum and chill of air-conditioning took over. A dozen solid walnut chairs sat around a huge oval walnut table. The room was carpeted with Axminster's finest, and it smelt like it had only just been laid. I wondered if it was the fruit of some kind of government initiative to boost local industry or Tresillian cocking his leg and marking out his territory. If they'd given Anna the cheque-book and an hour in Ikea she could have saved the taxpayer thousands.

At the far end of the table, below a vibrant plasma screen, I saw the world's most pissed-off face. There were far too many wrinkles in it for a man in his early fifties. His hair was thinning on the top and swept back. Either it was wet with sweat or he'd stepped straight from his office shower.