We arrived back in London on the morning of July 8. Though we'd come home regularly and for long periods during our time away, it was clear that the city we left six years before no longer exists. It's not just that Polish and Brasilian Portuguese are now the most audible languages on the buses. The tempo is different and the local securitocracy is consolidating its unholy grip. Luckily, they don't hang on to our microchipped pet cat for too long. Running around the local park I bump into Dan who I've known for 32 years, since he was a ten year-old on the rough end of a diagnosis as educationally sub-normal. Those were the days. Now, he's wearing a dusty hard hat and working doing demolitions because he can't find skilled work as a brickie. It seems to me that he and his peers have now been reconciled to the shit work that they rejected for so long. "It's those Eastern Europeans, Paul," he confides "they're putting the black man out of work". Sensing my surprise at hearing these xenophobic sentiments coming from his mouth he adds a weary 'no offence' and trudges off to his next falling building.

As I loop Finsbury Park the next day in the late summer heat, my running companions seem increasingly to be headscarfed Muslim women out to build their stamina. I wonder where the boys train. The park remains stubbornly what it was, in spite of some much-touted environmental improvements. It's still a testament to the basic ability of different folks to get along creatively and control their inevitable conflicts. I pause to watch two Turkish guys shooting hoops with two Hasidim. Perhaps we've all been wrong and basketball rather than football really is the world's game.

The Test matches have provided an absorbing reacquaintance with the one game I couldn't manage to hear for free online. Cricket commentary combines well with my unending task of opening cardboard boxes full of books and things I know I'd be better off without. I stroll along the Strand from my new office towards Trafalgar Square to watch what feels like being the historic feting of the triumphant team. This Anglo crowd is a troubling beast. There's something strange and zealous about their celebration. Their evident hunger for the recovery of England's long-vanished greatness suggests that the country is just one charismatic leader away from a huge political problem. Happily nobody is actually chanting "two world wars and one world cup".

Off to the Jazz Café to check out Medeski Martin and Wood: the improvising trio who's oblique and oversmoked instrumental funk meanderings derive from the epoch-making second-line pulse of The Meters. MMW never speak from the stage but, post-deluge, it will be interesting to hear them here and see how they go down without the cushion provided by the neo-hippy fandom that tracks them to and fro across the US. It was a shock when their set exploded with all the righteous anger of deeply disenchanted 'liberal' America. For an hour, their country's bitter mood is exposed and examined from different angles. Distorted, dissonant chord-fragments blister from Medeski's Rhodes piano as he rides Billy Martin's insistent, propulsive summoning of Crescent City traditions. Only after they've exorcised the spirit of just-dead Gatemouth Brown do they settle down into a steady groove for the crowd who came to dance. Perhaps Marie Leveau will intervene and claim the soul of vampire Dick Cheney as he lies on the operating table getting his aneurysms fixed?

It's now thirty years since Rock against Racism changed the pattern of cultural and political life in this country. Daughter and I head off to a screening of Who Shot The Sheriff? a new documentary made by Alan Miles, a young fireman, who feels it's time to revisit that history and make it speak to our perilous new circumstances. The film is powerful and moving and RAR's brave originators are out in force, rightly proud of their achievements. The film is shown again at a 'Love Music Hate Racism' gig later that night. After the credits roll, a reconstituted version of The Beat change the words of 'Stand Down Margaret' and sing "stand down Tony" instead. Too bad that when Eric Clapton recycled his vile opinions in a magazine interview earlier this year nobody said anything at all.

Daughter is applying to HE for next year so we've been visiting universities and checking out their English departments. The customer culture has acquired an amazing momentum. One of our most charming guides, another headscarfed Muslim girl, explains impishly that en suite is the new rule in the student accommodation and then talks sagely about the price of alcohol on campus club-nights. Memo to self: try to be more suspicious of anybody claiming that 'multiculturalism' is dead.

Paul Gilroy is the Anthony Giddens Professor of Social Theory at the London School of Economics