Genuine twin cities? Now that I'm here, I have to say that I have trouble seeing it. And it's not just the superficial differences that I'm worried about. That is to say, it's not just the fact that Oporto has Baroque churches, while Liverpool had the Cavern Club, or that the sun shines here while in Liverpool it rains. Or indeed that Oporto gave the world port while Liverpool gave it Pears soap.
I admit it: a working-class city of which the principal business is satisfying the after-dinner cravings of the British aristocracy is certainly intriguing. But before I go into a paroxysm of northern European paranoia about the quality-of-life thing (why exactly is it that people living south of a line running approximately from Bordeaux to Bologna always have much more urgent things to talk about than the rest of us do?), I am perfectly prepared to look on the down side of life in Oporto as well.
I am prepared to concede, for example, that some of the Porto FC supporters have unhealthily squashed noses. I also admit that the filthy Douro River is not a place where I would wish my worst enemy to swim. And, yes ,the young people of Oporto probably tire - at moments - of belonging to a relatively conservative, homogeneous culture, lacking in the buzz and excitement of a multicultural, multiracial society in the throes of change.
But all the same: would the people of Oporto walk around the decrepit, decaying bits of Liverpool (or indeed any other British city) marvelling at how charming and picturesque it all was? Because, like it or not, that's what you can't help doing here.
When I arrived on Thursday afternoon the first thing I did was check into a nicotine-stained hotel with dodgy wiring and a bed as creaky as a Spanish galleon. But it only cost pounds 10 a night with breakfast and I would gladly stay here for a month. Next I stepped straight into a cafe called A Brasileira which, to tell the truth, did not seem to have been painted since Brazil was discovered. The locals may, for all I know, regard it as a tragic symbol of inner-city poverty. But if this is the equivalent to a greasy spoon cafe, why does it have to have a marble-clad interior fitted with leafy flourishes in bronze? Why do self-important-looking senior citizens still sit in it? And why is it that from a strategically placed seat on the pavement I could not see a single woman walking past who did not look like a 25-year-old art student?
When I went down to the waterfront I saw Oporto rise up all around me. It seemed to be trying as hard as a city possibly could to be tough, working class and unpretentious, with its soaring, spindly iron bridges, its mouldy Baroque towers, its cheerfully medieval housing, its stenches, its miles of hanging laundry. And there, under stone arches right by the riverside, I found the local version of unemployment, single motherhood and homelessness rolled into one: old ladies selling the first apricots and cherries of the season, alongside piles of olives and bottles of port.
Well, at least "Strawberry Fields" wasn't written by a tripe-eater.