Mr Johnson then turned to a Chinese student, asking: “The yin and the yang. What do you say for a harmonious, sounds like one of those Chinese fireworks, a harmonious dove or something like that? A pair of harmonious doves. What is that in Chinese?”

After she looked back blankly, Mr Osborne said: “I think she likes the yin and yang comparatively.”

Earlier, the mayor could not resist a friendly dig at Mr Osborne, who in a speech at the university mentioned that his 10-year-old daughter was learning Mandarin.

Mr Johnson then told the same audience that not only was his daughter learning the language but also planned to visit China next week.

Mr Johnson said: “George mentions his daughter, I have a 16-year-old and she is not only learning Mandarin George, she’s coming here next week to pursue her studies.”

After the speeches, Mr Johnson proved more popular in a question and answer session, with just one question directed at Mr Osborne.

The mayor and the Chancellor have long been touted as successors to David Cameron as Conservative Party leader and their visits come at a time of thawing relations following a diplomatic row over the Prime Minister meeting the Dalai Lama last year.

Both Mr Osborne’s and Mr Johnson’s trips have been in the pipeline for months but the timing of the Chancellor’s visit was revealed more recently than the mayor’s.

Yesterday, Mr Johnson stressed he was “very pleased” that Mr Osborne was visiting while admitting the timing was handled by the Government.

Sources: ITN/PA

And yet for millions of people who have to use buses every day – and who have no choice about which mode to use – the feeling is very different. If you have to use public transport morning and night, then you know that it can take a huge slice of your income – and that is why we politicians cast around so desperately for ways to reduce the burden.

Every autumn we face the same dilemma. If we follow the pleas of our officials, and raise fares – to cope with inflation and the cost of investing in our systems – we are tightening the squeeze on people who have already seen their disposable income shrink over the past five years.

If we are irresponsible, on the other hand, and we fail to replenish the “fare box”, then we risk disaster. We are coping with the oldest underground train network in the world, and with a city that is growing faster than any other European capital. If people are to have any hope of living near their place of work, we have to supply them with adequate trains, buses and Tubes. We cut costs at every opportunity – selling buildings, introducing automation, axing bureaucracy – but the trouble with a universal fares freeze is that it takes a huge chunk out of the budget. It means indefinitely postponing or cancelling schemes that are essential for growth, such as replacing the clapped-out signalling on the District line, or ordering new trains for the Piccadilly.

And then there is a second problem with an across-the-board fares cut – namely, that it is a hopelessly blunt instrument. Think of me luxuriating there on the Oxford Street bus, on my once-in-a-blue-moon shopping trip. Do I need a fare cut? Think of the millions of tourists who use our transport networks every day, and who probably don’t even notice how much they are paying. Would they be any more inclined to come to this country if the cost of their urban transport was a little lower? Do they need or deserve an abatement in their fares? I don’t really think so.

Look around you on the bus, and you will see that almost 40 per cent of the complement are travelling free or at cut price: the pensioners with their Freedom Passes, the kids, the veterans, the disabled, those in search of work. No politician is easily going to remove these concessions (try telling the affluent bourgeoisie that their Freedom Pass is at risk, and see what mayhem ensues).

The result is that the entire burden of fare-paying is carried by the 60 per cent – and that includes the people who make this country work, the people on low or moderate incomes who travel large distances every day to their places of employment and who have absolutely no choice in the matter. It is time we did something specifically to help them, and that something is to give tax relief on travel.

We need a scheme that is analogous to the government help currently given to child-care vouchers or cycle-to-work schemes. Employees should be allowed to pay for their season tickets from their pre-tax income.

To see what I mean, take a customer who buys an annual bus pass for £784. At present, he or she buys that season ticket after paying tax. Under the tax relief scheme, the employer would buy the season ticket and deduct the cost from his or her pay packet – and only then would the employee be assessed for tax. With their taxable pay reduced, the employee would save £251 in tax and National Insurance, and the employer would save £108. The administration costs would be kept minimal by doing it all online, and of course the relief would only apply at the basic rate.

Yes, there would be a cost to the Treasury – but then every year the government spends huge sums trying to hold fares down. This scheme strikes me as one George should consider further. You would allow continued investment in transport, and you would target your help at exactly the people who need it – not the millionaires and the tourists and the casual shoppers, but the hardworking people who are really turning the wheels of recovery.

Boris and David Cameron are supposed to be on good terms at the moment – the Prime Minister even told the Today programme that Boris should “absolutely” be an MP again. After the speech, a mob of journalists – or, if you prefer, a ginormous convocation of worms – followed Boris round the exhibition hall, asking him whether he agreed. He didn’t seem desperately keen to answer.

Would he look for a seat in 2015? “There’s been no change in what I’ve said in the last five years, and I’ll continue to say it until I’m blue in the face and blue in every other portion of my anatomy!” What seat would he like? “It’s got a kind of spongy bottom, and it swivels, and it’s to be discovered in the office of City Hall!” Was he going to keep fudging the question? “Yes.”

Around the hall, little old ladies looked up from their tea, waved excitedly and trilled, “Ooh, hello, Boris!” Others pointed admiringly at his hair, which more than ever resembled an upturned colander of spaghetti. Goodness knows how he gets it looking so messy. It must take hours of preparation.

Fortunately for the convocation of worms, when Boris is in what Bridget Jones calls “full autowitter” he generally blurts out a gobbet of truth sooner or later. “My leadership chances, as I may have told you before, are about as good as my chances of being reincarnated as a baked bean. Which are probably quite high, actually…”

What did it all mean? Was Boris really plotting a Westminster comeback? Or had he privately concluded that Mayor is the job that suits him best: maximum publicity, minimum pain? Does anyone know? Does Boris?

Urb urb urb murm murm.

And now, in an incautious admission, he has reminded us of his core beliefs – as the proud son of a Marxist academic. He wants to restore socialism to Britain. In spite of everything, the mission of Labour under Ed Miliband is to revive a political belief system that brought Britain to its knees, that blighted the lives of hundreds of millions of people in the former Soviet Union and Eastern Europe, that was responsible for untold murders and abuses of human rights, and that in the past 30 years has been decisively rejected across the planet in favour of liberty, free enterprise and market economics – a rival system that has lifted and is lifting hundreds of millions of people out of poverty and servitude. Someone needs to tell Ed Miliband that socialism failed, and I have just the man to do it.

I happen to think Mr McBride is genuinely repentant, and I know that he is working hard for good educational causes in London. But if he is to achieve full redemption he needs to think about why he behaved in that way. What was it that legitimated – in his mind – this hideous trampling over all norms of decency? He smeared ministers who seemed to stand in his way, he destroyed careers, he wrecked family lives. It seems incredible that a highly intelligent man could act like this just because he adored Gordon Brown. No, that wasn’t enough: he justified his ruthless actions to himself in the same way that socialists have always justified their ruthlessness – that the end justified the means.

And that is the problem with socialism. It has always involved the use of revolting means to pursue an unattainable end. It has seen the rights and liberties of individuals trampled in the name of a collective good. Damian McBride is a small but interesting example of the mental contortions of socialists over the last century, when there is no abuse or tyranny – large or trivial – that has not been justified in the name of the people.

When the Securitate persuaded children to inform against their parents in Ceausescu’s Romania, they knew – at one level – that what they were doing was creepy. But they believed it was in the wider interests of the state, and therefore of the people themselves. When thousands of Soviet dissidents and bourgeois reactionaries were hauled off to perish in Siberian gulags, the authorities knew – with one side of their brains – that this was morally no better than Nazism; but they persuaded themselves that it was for the greater good, and that you could not make an omelette without breaking eggs. When the North Koreans shoot anyone who falls foul of their deranged and psychotic regime, they don’t blame their evil dictator; they think – or at least they assert – that they are protecting a system of government that is morally superior to that of South Korea and the rest of the capitalist world.

I don’t mean that Ed Miliband will try to import some new form of Stalinism to Britain, or that we will see the systematic abuse of human rights. British socialism has always been a much milder strain. But the fundamental impulse is there: to use regulation or coercion to try to impose an idea of equality, when the result is the exact opposite. Why has social mobility declined in the past 30 years? Why is it that there are fewer children from poor backgrounds who make it all the way to the very best universities than there were in the 1960s?

Because – in the name of equality – Labour politicians launched a war against the grammar schools and indeed against the whole competitive ethos in education. How is a dose of socialism going to help us improve our schools, or reform the welfare state, or get a better deal from the European Union? The most important political fact since the crash of 2008 is the complete failure of the Left to provide any realistic alternative to the free market economics that have been adopted across the developing world, and that have seen a huge rise in living standards for billions.

It has its chance to offer a new model – and we have heard nothing. Now we have Ed Miliband telling us that his plan is to go back to Brownite “socialism” – the over-borrowing and over-spending that got us in the mess in the first place. Why hand back the bridge to the very people who ran the ship aground?