Yasmin Alibhai-Brown: Our most precious possession

Post-colonials and their children in Britain have reclaimed English and made it their own

Our Prime Minister and his Coalition squires had to answer some tricky questions in China about their increasingly muddled immigration policies, which, depending on the day, case, person and place, appear to be tough and pragmatic, or unfair and cruel, or open and generous, or abstruse and mercurial.

Chinese millionaires are welcome of course, but not the poor. Yes please to high fee-paying university undergraduates; but no to those wanting to go to private language schools, which are all now seen, unfairly, as stopovers for illegal migrants and traffickers. Three years ago, polemicist Christopher Hitchens asked on Question Time: "What do we have that is better than our language?" We have 85,000 Chinese students in the UK. Many of them want our most precious product. Are we really going to deny them that gift?

I can speak four other languages which my children refuse to learn. Saddened by their indifference and wilful ignorance, I can understand why. I could not communicate the thoughts in this paragraph in Hindi, Swahili, Gujarati or Kutchi. English has infinite reach and depth. You grow into it; it grows inside you until it reaches your dreams.

And now, at long last, a fitting homage to this linguistic story – an exhibition on the marvels of English at the British Library. It takes us from its beginnings in the fifth-century, through the accretions and adaptations, the porosity that let in Latin, French and Germanic words, great English wordsmiths like Bede, Chaucer, Shakespeare, and Johnson, Caxton's printing revolution and on to now.

There are many delights and surprises – "yobbo" goes back to 1921; "fat cats" to 1928, and "sleaze" to 1967. You can hear audio-versions of how English sounded in past eras. The Empire spread it and colonised liberationists' tongues – Gandhi, Kenyatta, Jinnah, Nkrumah. Subjugated nations appropriated the lingo, added music of their own, rhythms and miscegenated vocabulary.

Post-colonials and their children in Britain have reclaimed English and made it their own. There remain South Asian Britons, though, who fear Anglicisation and will not open up to infinite possibilities. What a waste. They cannot, thankfully, stop their young jumping into the inviting ocean that is English and the access that gives them to modern life.

Last week I went to see the buddy thriller Pune Highway, by the Indian theatre company Rage, at the Watermans Arts Centre in Brentford. I saw it again three days later. Playwright Rahul da Cunha exposes the degeneracy of contemporary, moneyed Indian society. Actors Rajit Kapur, Ashwin Mushran and Bugs Bhargava Krishna brilliantly play three friends with no moral compass. Their crude, pared down English lacks compassion or grace and becomes a metaphor for India's fast, thoughtless and furious globalisation. It is as powerful and challenging as Look Back in Anger must have been in 1956, or Pinter's early work. It is English again, breaking out and starting out a new trajectory in its unending history.

French and Italian don't have that capacity. David Crystal, world expert on English, told me it was because those languages opted a long time ago for strict protectionism, but ours is the opposite, with all doors and windows open.

The future looks bright then, until you notice those who use new technology without due care. Some crazed demons on Twitter believe anything goes. Written words matter and hold meanings beyond that narcissistic urge to send off instant thoughts. The Tory councillor who sent out a vile and scary message about me says it was a joke. After some thought I decided I will not press charges. My objections have been made and there is no need for more. Yet having read many blogs and tweets that followed the incident, I do wonder whether our manners and morals will survive and if English itself, the best thing about us, is now seriously endangered.