Yasmin Alibhai-Brown: So, is Britain too multicultural now?

Jesus! More multicultural crap! More bleedin' foreigners winning our medals! Even cheering with indecent enthusiasm for Team GB! Who the hell do they think they are? And what the hell happened to this great nation? Tory MP Aidan Burley, an immigrant from New Zealand, dissed Danny Boyle's inclusive opening ceremony in a tweet. By now he must be spitting his (probably whitened) teeth. So too the risible journos who've been whinging about "plastic Brits" in the team, an obnoxious term invented for competitors not born in the UK. Like the South African Zola Budd, a white athlete who, during Apartheid, was given British nationality so she could run for Britain. The Daily Mail made it all happen for that "plastic Brit". But today intolerant right-wingers question the motives of non-indigenous sportspeople and are furious they have been chosen to represent the UK.

Golden Saturday must have been a bit uncomfortable for this awkward squad. Mixed feelings must have curdled the patriotic juices when Mo Farah, born in Somalia, won the 10,000 metres, hugged his daughter and pregnant light-skinned wife. And when he pronounced himself the proudest of flag-wavers. Or when Jessica Ennis, the daughter of a black father and a white mother, wept as she received her gold while 80,000 fans cheered and belted out the National Anthem.

I wonder how the formidable anti-immigration prophets and campaigners react when medals are won by super-fit migrants and children of migrants? Do they feel collective resentment that a Somali running off with a medal deprives real British talent, which will, as a result, give up and sit in front of the telly for ever with chips and fizzy drink?

Maybe they're like my father who was fantastically proud and claimed me as his daughter only when I got good grades – and the rest of the time arraigned me for being too much trouble and my mother's child. Even over this extraordinary, internationalist fortnight, when the world is in Britain, seeing the best of the British, some surly jingoists will not accept what their country is and will not let those who made their lives here or who identify with the nation ever, ever feel they can belong or represent GB.

Tiffany Porter, the injured hurdles hopeful, whose parents are black British, has faced humiliating tests of loyalty; Cuban Yamile Aldama, triple jump finalist, married to a Scotsman, waited a decade to get British citizenship. Both have felt accused, their integrity sullied by malodorous innuendo for being who they are, not what they are trying to achieve. Aldama is hurt by it: "When I joined the team it never crossed my mind I would get a reaction like this. I feel part of this country. At home we have roast beef dinners on Sunday."

Instinctive native excluders are as big an obstacle to social and national cohesion as black and Asian separatists. Maybe more. David Cameron and others are ever-ready to chastise "non-integrated ethnic minority communities". Nothing wrong with that per se because we do have some ghettoisation, and that is a concern. But in the name of fair play it would be good to hear these leaders just sometimes ask white Britons to treat us genuinely as their compatriots. OK, so Burley was slapped down, but it was too feeble a response in my view.

Seb Coe, one of my current heroes, has spoken movingly about how the opening reflected a nation with a "quirky sense of humour, a love of eccentricity, a sense of fair play and the embracing of multiculturalism". Surely now is time for a nicely turned prime ministerial speech on what immigrants have brought to team GB. Maybe he could start with Joseph Addison who wrote in 1711: "It gratifies my vanity to see such an assemblage of countrymen and foreigners consulting in the private business of mankind, making this metropolis a kind of emporium of the earth". Millions from that emporium came, settled, injected fresh blood into the body of the amazing nation, added music, riffs, colour, vitality and unbeatablity.

The story of this nation is one of continuous exchange between here and abroad, them and us and them who are us. The first man to win a medal for GB was Charles Gmelin, born in India to missionaries. Bradley Wiggins was born in Belgium and so on and on. There are nurses, doctors, scientists, writers and artists now claimed by this country who started life elsewhere – or maybe they too are "plastic'" here only to get money and fame and steal the future from the true-born.

I know of the problems – boy, don't we all. Day after day, we are woken by the Today programme telling us how bad migration is, how bad we migrants are, as do most of the papers, fiendish trolls, the far right and some nicely spoken, respectable citizens too. You'd think we are all terrorists, sex offenders, killers of daughters, illegal entrants, alien criminals, and procreators of too many more of the above. The abuse heaped upon me for being an Asian Muslim incomer with attitude would kill and bury me if I let it. We fight back because we are worth it and so is the state we live in. That poetic paradox may explain why immigrants don't give up.

On Friday evening, getting on to a tube in Victoria, I met a Somali family wearing so much Union Flag kit they looked like a mobile tourist stall. The mum had a red, blue and white band across her forehead under a tight, black head scarf; her sons carried flags and her daughter's leggings were festooned with crowns, Big Bens, St Paul's and colours of this nation.

They were coming back from a halal chicken restaurant after breaking an 18-hour fast for Ramadan. They told me they were so happy because of Farah. They wanted their children to be like him, make this country proud of them. Near us a white family was just as joyous and for the same reasons. And I thought, this is brilliant, we are in it together.

And then a smart-looking white woman in her forties muttered to a man she was with: "They're not British. How dare they? Why don't they go back where they came from?" Then got off at Sloane Square. You see, we immigrants can't win. But we'll never stop trying.