Last Night's Viewing: Victoria Wood's Nice Cup of Tea, BBC1 The Century That Wrote Itself, BBC4

Crikey! For a moment, I thought she was going to do it. I believed that Victoria Wood was going to inhale opium on primetime TV. That's one up on Keith Allen and his live MDMA trip – all very late-night Channel 4 and self-consciously daring.

But this? What would Wood's dinnerladies heartlands think? Would they have to put it in their pipes and smoke it? The moment came halfway through the first episode of Victoria Wood's Nice Cup of Tea – a cosy title for such a surprisingly astringent brew.

Tea was originally the preserve of the Chinese, who kept its botanical origins a strict secret from acquisitive merchants from the increasingly cuppa-crazy English. No Europeans were allowed inland from the ports, and the Chinese had no use for traditional British trading trinkets such as knives and forks. What to do?

Why, get the Chinese hooked on opium, of course, for which they would soon be willing to trade their mothers along with their tea. As Wood observed: "Victorian Britain became the biggest drugs dealer in history." The poppy extract in question was imported from the north-east of India, Assam to be precise, which is where Wood found herself sitting down to table in an opium den, and I genuinely thought for a moment that she was going to join the wizened old smokers preparing for a pipe. It would be rude not to.

One assumes she didn't, although the scene seemed oddly truncated as we cut straight to the bush, whither the narrative had progressed. For it seems that the British now wanted to cut out the middleman. They wanted to grow tea in their own back yard, which, in the 1830s, included India. And it turned out that Assam had its own indigenous tea plants – a type of camellia, by the way. And a tree, not a bush, if you don't bother to prune it. Did I tell you this was fascinating stuff?

The great things about Wood are that she doesn't labour her points, she doesn't throw her hands around in the air (where do they teach that?), and she's genuinely funny. I loved her description of the Shanghai restaurateur serving her tea-flavoured vegetables as "the love child of Mary Quant and a Bond villain". Somehow, Wood managed to make it not sound cruel, and when the lady in question stood revealed, I burst out laughing in recognition.

The programme wasn't without poetry, and this is Lu Yu, writer of the eighth-century tome The Classic of Tea, and his prescription for a perfect cuppa: "It must have creases like the leather boots of a Tartar horseman, curl like the dewlap of a mighty bullock, unfold like a mist rising out of a ravine, gleam like a lake touched by a zephyr and be wet and soft like a fine earth newly swept by rain." Not sure British tea drinkers would buy that – even in Waitrose. Bring on the performing chimps.

Our nation first discovered tea in the 1600s, at the same time it was discovering written self-expression, the subject of author Adam Nicolson's enjoyable new series, The Century That Wrote Itself. Nicolson recounted five individual stories from this "first great age of self-depiction", literally taking pains into breathing life in what might have been just sequences of him reading out their words.

And so he pricked his finger with a pin and signed his name in his blood – in emulation of Sir John Oglander – a monarchist landowner living in a Parliamentarian Isle of Wight, and whose financial accounts gradually turned into a personal diary. Oglander spilled his blood over his son's eye-watering holiday expenses. When the same favoured child died unexpectedly, he wrote his name in tears. I'm glad to say Nicolson didn't attempt to copy that.