When I first met my Aunty Ada – my Dad Bill took me up to Birkenhead to meet her, along with Peggy, my Mum – she did nothing but pour cups of tea. Ada ran a shoe store but spent the entire day with us. Tea. Tea. "Another cup of tea, love?" And she wouldn't take no for an answer. "Good God!" Bill exclaimed later. "Did I drink that much tea when I lived up here?" He thought maybe tea had caught on in Liverpool because that's where the old tea clipper sailing ships – on which my grandfather Edward sailed – arrived from China. And tea, of course, originally came from China, invented in 2,750BC after the leaves of Camellia sinensis accidentally fell into a bowl of hot water in front of the Emperor Shen Nung. He liked the smell and poured himself the world's first cup of tea.

True to all British history, we took a long time to catch up. Our first tea came from Holland in 1650, initially referred to as "tay" from the Dutch thee, a version of the Fujian t'e. This I have on the authority of a fine and unique academic treatise on tea by one A R T Kemasang who is soon to publish an entire book in Indonesia (of all places) on China's role in civilising the West. In eastern Europe and in the Arab world it became known as chai from the Cantonese ch'a. Where I live, in Lebanon, the chai is served up in kettles, already swamped with sugar – though never served with milk.

A secret, now, from the Arab world. Western soldiers in the Middle East are always encouraged to drink 12 litres of water every day. Long ago, in the deserts of Syria, Jordan and Saudi Arabia, I learned differently. The Arabs will drink tea at dawn to warm them up – often poured from a great height, at arm's length – and then they will drink tea in the burning heat of midday to cool them down. Then they will drink tea at dusk to warm them up again. I do just the same on my balcony in Beirut. It works. "Water makes you perspire," an old Syrian friend once told me. "Then you have to drink more water to make up for lost water. They you perspire again..." (So is there a military conspiracy going on here, I wonder, by the bottled water companies?)

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The East India Company brought tea to India in the 19th century and enjoyed a brief monopoly in the British Isles until Charles Bewley turned up in Dublin with 2,000 chests of the stuff in 1835, directly from China. Earlier, the Great and the Good of English society had actually condemned the stuff. William Cobbett (he of Rural Rides) and Methodist John Wesley (who thought tea caused "paralytick disorders") treated tea as if it were alcohol. Sydney Smith, however, gave it a seal of approval. "Thank God for tea!" he announced. "What would the world do without tea? I am glad I was not born before tea." And I can see why. As Kemasang explains, before tea there were few ways to keep warm in England. Water was filthy and disease ridden. The mass of Britons shivered all night in their unheated homes. Kemasang quotes a 15th century schoolboy whose diary entry reads: "The moste part of this winter my handes were so swellynge with colde that I coulde nother holde my penn for to wrytt nother my knyff for to cutt my mete at the table."

Milk had its problems too. Here's Tobias Smollett on the trade in fresh milk which is "carried through the streets in open pails, exposed to foul rinsings discharged from doors and windows, spittle, snot, and tobacco quids... overflowing from mud carts, spatterings from coach wheels, dirt and trash chucked into it by rogueish boys... the spewing of infants...". Yes, I shall stop here, for it is Saturday morning, O Reader. I shall not mention here the American predilection for coffee, nor the Boston Tea Party which arguably lost us America. Think only of tea.

What words it brought us. A Hokkien weight unit equivalent to just over a pound was called a kati. Hence our tea caddy. But wait. Time for a diversion. How many readers know that in 1859, fighting off the Indian mutineers, the British army found that its soldiers – wearing white, of course – were being cut down by musket fire. Soldiers were thus ordered to rub brown dust into their uniforms. The Urdu for dust is khak. Thus we now dress our soldiers – even in Afghanistan today – in khaki uniforms. I thought I'd reveal this after reading it in an Egyptian newspaper the other day. And one more for the road. Rereading my schoolboy's copy of Group Captain Johnnie Johnson's Wing Leader this week – he was the top-scoring Allied flying ace of the Second World War – I found that the emergency "Mayday" comes from the French M'aidez!.

Before tea, needless to say, millions of Brits warmed themselves with alcohol – which only gives the illusion of warmth. The real effect – as Kemasang makes perfectly clear – is that most people were drinking cider, beer, gin or wine most of the time and were most of the time inebriated. Even the Crusaders, some say, were drunk when they rode into the Holy Land. Molière, La Fontaine and Racine drank wine. A hundred years later, Beaumarchais and Voltaire were drinking tea. In the 18th century, London was unsafe after dark. Hogarth's Gin Lane shows what it was like during the day. Tea changed all that. A sober working class could labour for long hours in the great factories and mines and shipyards of the industrial revolution. Hence tea helped the British Empire to grow economically into the strongest power on earth.

It was a poor Lebanese family in southern Lebanon that first insisted to me that tea could prevent cancer. And subsequent research – especially in China – suggests that this is absolutely true. Especially green tea, though this is more popular in Afghanistan and Pakistan than in the Middle East, where they like it black and strong. So do I these days. No Arab meal can be concluded without it. And now it's like a narcotic for me. Writing a feature at 6am in Los Angeles or a report in Tehran at 11pm, I send for a cuppa. My Aunty Ada would have agreed.