Ken Livingstone was the mayor London needed on 7/7

I was in Serbia when the London bombings happened. I'd been travelling with a couple of guys I'd met on the road. We booked into a hotel and I switched on the TV. I remember being kind of excited about it. I hadn't watched any TV in weeks.

The first image when the screen came on was of a red double-decker bus with its top blown off. I couldn't understand anything that was being said, but the pictures told me everything.

Afterwards there was that flurry, familiar to many of us, of desperate attempts to get hold of friends and family on the phone and make sure they were OK – no easy task without a mobile phone in a dingy hotel lobby in Belgrade. But once the personal terror of having lost someone close to you has faded – if you are lucky enough to be one of the ones for whom it does fade – the broader, indirect sense of personal loss takes over.

I was desperate to be back in London. Every proper Londoner has a deep, unyielding loyalty to the city, but it is not something we talk about very often. That's not the British way, and for all its global, outward-looking qualities, London remains a decidedly British city. Yet when it is hurt, all Londoners – even those who have not lived in it for years – feel the need to return to it. London becomes a person you know. When it is ill, you want to be by its bedside.

I wasn't with any Londoners. And nor honestly was there all that much sympathy. Serbia had, not so long beforehand, been the target of Nato strikes in which Britain had played a prominent role. People were not unkind. They were respectful. But if I had to be away from home when this had happened, Belgrade was not the place I would have chosen to have been.

And then Ken Livingstone's speech was played on the news. Annoyingly I can't find it on YouTube (although some of his more formal speech, in Trafalgar Square a few days later, is embedded below and is also very good). But you can see a short clip of it on this link. You can also read the full speech here. It was a moment of genuine leadership, the leadership of ideas and sentiment, which cities and countries need when in peril, but so rarely get except in the most cynical and self-serving way. It offered a sense of belonging, so that even from far away it made me feel as if I might be at home.

The mayor was in Singapore. The way he looked and spoke was more important than what he said. He looked shattered. He looked harrowed in a way that couldn't be impersonated. This was not a politician adopting the sombre tone of loss and national tragedy. This was a Londoner, broken by what had been done to his city. At several points he seemed like he might cry. He looked like a man who was going through what I was feeling, not a politician who wanted to give me the impression he was.

This is what he said.

"I want to say one thing specifically to the world today. This was not a terrorist attack against the mighty and the powerful. It was not aimed at presidents or prime ministers. It was aimed at ordinary, working-class Londoners, black and white, Muslim and Christian, Hindu and Jew, young and old. It was an indiscriminate attempt to slaughter, irrespective of any considerations for age, for class, for religion, or whatever."

It was important that he said  'working-class'. Tony Blair wouldn't have said it. Boris Johnson wouldn’t have said it. It's not the class-consciousness that matters and it's certainly not a belief that it's somehow worse to target someone working class than someone wealthier. What mattered was that he was being specific. His speech had content. These were not platitudes about 'freedom' and 'our way of life'. There was meaning there.

The people they killed were those who got up in the early morning and rubbed their eyes and wanted to go back to bed but didn't and got on a rush hour Tube like the rest of us. People who tried to read the paper in between someone's arm pit and wanted the day to hurry up so they could be in the pub or back home with family. They were workers. They were not 'hard-working British families'.

Livingstone then addressed himself to the terrorists themselves.

"In the days that follow, look at our airports, look at our seaports and look at our railway stations and even after your cowardly attack you'll see that people from the rest of Britain, people from around the world, will arrive in London to become Londoners and to fulfil their dream and achieve their potential. They chose to come to London, as so many have come before, because they chose to be free. They come to live the life they choose. They come to be able to be themselves. They flee you, because you tell them how they should live. They don't want that. And nothing you do, no matter how many of us you kill, will be able to stop that flight to our cities, where freedom is strong and people can live in harmony with one another."

He understood the great truth of the city. It is the great changer; the furnace. It's the place you come to be something other than what you were before you arrived. It's the place where you do not have to be defined by your childhood, or your relatives, or the job your parents did, or your accent, or your religion, or even your schooling. It is not a warm or a caring place. It's brutal and anonymous. But it's the place you get to start again. That's why London is such a powerful engine for business and art and academia and science and culture. Not because of the number of people in it, but because of the type of people in it. The city is where you come when you want to make something of yourself.

Livingstone expressed that better than any of his contemporaries could have, but he was also better placed to do so. Because embedded in the DNA of that speech is a love of immigration, of people who move – not just between countries, but within countries too. It could not have been made by a politician who spent their days fearfully placating the little-Englander prejudice of Daily Express readers outside London. It could only have been made by someone who truly believed in immigration and the way it had built London, from its very first days to its current ones.

It could not have been made, in all sincerity, by Boris, who speaks pro-immigration language as mayor but switches to the same drab anti-immigrant message as everyone else when cultivating his national political ambitions. And anyway, the current mayor is too clever and cynical to ever be able to channel the feelings of a city, as he proved with his hapless response to the London riots.

The speech could only have been made by someone who really understood what London is: a British world city.

And now that British politicians turn their back on those desperate people getting on broken boats for a slim chance of reaching London, that speech reads more powerfully than it ever has. They still come, every day, often risking their lives, to find a place where they are truly free. On one of its worst days, London was lucky to have Ken Livingstone in charge.