Grand old duke who defined a certain essence of Englishness

I fell in love with a man in France, not something I do normally. I had a few days there by myself reading in the garden and spent most of it with Christopher Hibbert's biography of the Duke of Wellington.

What a man (the Duke, I mean, though Hibbert clearly has his virtues too). What a magnificent character, the greatest man in England for years; he may have even been the inventor, the progenitor of a certain sort of Englishness, that perfect self-possession, that sang-froid, that unbending rectitude that made us so unpopular all over the world.

"By God, sir, I've lost my leg," one of his officers said at Waterloo. The Duke's reply is well-known ("By God, sir, so you have!") but the thing to remember is that Lord Uxbridge was imitating the Duke in a way that airline pilots for years imitated – vocally at least – the test pilot Chuck Yeager.

Wellington's indifference to danger infected the whole officer corps. His battle staff at Waterloo seemed "as gay and unconcerned as if they were riding to meet the hounds in some quiet English county". He had encouraged a hostess to have her ball on the eve of the battle; the party went on to such an hour that some officers appeared on the battlefield in their dancing shoes.

It all so amazed the Prussians that they went out of their way to imitate him too. He may have invented the entire European military tradition.

Gruff, short, brutally laconic he could be, yet also capable of great delicacy, at least for a military man. When his principal aide-de-camp had his arm cut off, the Duke replaced him with another one-armed officer, to reassure his ADC that his disability was no disbarment to active service.

And was he coarsened by battle, by slaughter? Not entirely, maybe not even largely. He was woken from his first sleep after Waterloo by the surgeon John Hume bringing him the list of casualties. The Duke stretched out his hand as though in need of comfort. Hume took it and held it in is own as he read the names on the list. The surgeon soon became aware of tears dropping on their clasped fingers. He looked down to see them still coursing down the Duke's still dirty face, and paused in his reading. "Go on, go on, for God's sake go on," the Duke said. "Let me hear it all. This is terrible."

Among his many likeable traits was a voracious sexual appetite. Married to one of the silliest Pakenhams of the century, he availed himself of a significant proportion of the female peerage, as well as the great courtesans of the day. Lady Capel complained that he had "not improved the Morality of our society. He makes a point of asking all the Ladies of Loose Character to his parties."

For many years his liaison with Mrs Arbuthnot sustained him. When she died he went unasked to Mr Arbuthnot. It was another example of his tact. Mr Arbuthnot wrote the next day: "I am very glad you came to me instead of writing to propose it; for had you, I must have said no." He went on to declare that "life to me is from this day a blank". The Duke suggested they live together, and Mr Arbuthnot moved in with his late wife's lover for the rest of his life.

He didn't allow his troops to cheer him, observing that it might encourage them to think they had the right to boo him in other circumstances. When the Oxford hierarchy cheered him endlessly in the Sheldonian, he merely remarked: "If I could be spoilt by this sort of thing, they would spoil me here."

A great European, he knew the heads of Europe, eastern Europe and Russia and negotiated complex treaties with them all. He carried the Catholic emancipation as Prime Minister, persuaded his fellow Tories not to oppose the Reform Bill and lent his prestige to the repeal of the Corn Laws. He may have been the archetypal Conservative, but he was never a typical Tory.

He once found a boy crying in his garden. The child was being sent away to school and feared his pet toad wouldn't survive. The Duke undertook to look after the toad, and did so, writing to the boy at school to tell him how the toad was getting on. After all the grandeur and the great affairs of state, it was the toad that did it for me.

The public school ethos and the rebel in me

The film If... was on television over the weekend. It's held up reasonably well over the past 35 years, as a portrait of public school life. The squalor was particularly evocative.

It wasn't all so familiar. We didn't call fags "scum"; we didn't warm lavatory seats for our superiors; the fellow with the cane there didn't use a three-step run-up to beat you; and the absence of vicars in a long drawer in the headmaster's study was quite marked.

But things were changing fast. The term before I arrived, prefects were still allowed to beat boys. They were cruel, entirely unfeeling. "It's nothing in particular you've done, Cowling," the head of house said to my friend Cowling. "It's your attitude." That was very like the sentence pronounced on Travis in the film. The prefect (so brilliantly played by Hugh Thomas) denounced Travis for "sitting there, looking at people". Oo yes. Asking for it.

When Cowling became head of house in his turn, he refused to have a fag at all. I think the boy volunteered to fag for me, even though I, for obvious reasons, wasn't a prefect at all. Things were unravelling fast by then. The whole structure of society was changing. I never got up for breakfast, but slumped into the bath run for me by Vickers or Elliot. It didn't seem to do any of us any harm.

Having now fallen in love with the Duke of Wellington, I'm less critical of the old public school ethos. If only the authorities hadn't been so stupid they might have charmed us into obedience instead of saying things such as "I don't expect you to take pride in the school; I expect you to take pride in yourselves!" We just bobbed our heads and let lank and rather loathsome hair fall over our smirking faces.

The officer class had lost its confidence. Sergeant-Major Ludford (ex-regular army), by contrast, managed to inspire complete, unconditional grovelling obedience. "Simon," he said to me once in the armoury (and no adult at school had called me by my Christian name before), "I like you. You're a rebel. I'm a rebel. I've been a rebel all my life."

More heads took early retirement or had nervous breakdowns in those years than at any time before or since. None of them had Mr Ludford's skills in man management. If they had, the Sixties might never have happened.

Until the Tories regain this crucial sense of charm, they'll be dead in the water.

Donmar casting decision is a real eye-opener

The new chief of the Donmar Warehouse has cast the Nigerian actor Ejiofor Chiwetel in the lead of Noel Coward's play The Vortex. There's no necessity, of course, to have the part of the upper-class degenerate played by a white person (other than the fact that the character's parents are both played by white actors). But the reasoning behind is odd, to say the least.

"I realise that having Chiwetel will raise some eyebrows as it is casting against racial convention," the Donmar's Michael Grandage is quoted as saying. "Yet I hope the time will come when people don't notice whether an actor is black or white." Selective blindness, willed ignorance, ideology-inspired disability – are not these the things that theatre fights against?