I paid my bill and followed him through the lobby. Guests were returning from the theatre and dinner, discreet security guards watched from the corners of the lobby, ensuring all was well.

They did not look twice at the man I followed through the revolving doors of the Langham’s main entrance.

A black Mercedes Benz was waiting outside. The man from the bar brushed past the Langham doorman and held the back door open for me. As I settled myself in the car, the uniformed driver turned to offer me a silver tray with a hot towel. The man on the pavement waited until we pulled away, acknowledging our departure with a small bow. The driver asked me if I was happy with the temperature in the car, told me about the Wi-Fi that was available and then fell silent as London glided by like a series of old-fashioned postcards.

Broadcasting House. Marble Arch. Park Lane. Buckingham Palace. All lit up to inspire awe in the passer-by. At this time of night, it took just twenty minutes to the river. The Hopewell Centre soared fifty storeys high on the far side of the Thames, a circular tower of glass and money.

The driver murmured, ‘Five minutes,’ into his headset as we crossed Westminster Bridge. Then we were too close to the building to see it. The Mercedes eased down into the underground car park where another polite young man in a suit and tie was waiting with an iPad.

‘Mr Dempsey? This way, sir.’

We walked to a line of lifts. There was one that exclusively served the penthouse. The man with the iPad stood back as I entered, holding the lift door for me, and then stepped inside and swiped a key card. I wondered how our people would access the top floor without a key card, and then I stopped thinking about it as the lift rose above ground level and suddenly all of London was spread out below. We rose above the city so quickly that I felt the pressure in my ears.

The man with the iPad smiled at me.

The lift gave a discreet ping and the door slid open at the end of a long, hushed hall. A wider, larger man was waiting at the far end of the corridor. He rang the doorbell to the penthouse suite as soon as he saw me coming.

‘Enjoy your evening, sir,’ said the man in the lift, and the doors closed silently behind me.

Madam Theresa was waiting in the doorway.

‘Mr Dempsey! How kind of you to join us!’