A mild panic on Saturday lunchtime as I’m getting ready for the big British Museum ball. First, the dress code is ‘red’ and, though I’m due on stage in hours, all I’ve got is a black tie. Second, I haven’t watched last night’s episode of The Celebrity Traitors, and someone at the party is bound to tell me what happened. So I dash to a florist to get a red flower for a buttonhole; then I speed-watch on iPlayer. Thank goodness I did, because who do I meet at the ball? Maya Jama – Traitor-in-Chief. First she compliments me on the flower, even though it’s so lame compared to her outfit, and then she’s telling me the ins and outs of her murders. Never meet your heroes, they say. What nonsense. David Cameron and I could have done with a few Mayas round the cabinet table back in the day.

Politics hung quite heavy over David’s 50th birthday ten years ago. Lovely as the Cotswolds dinner was, our exit from Downing Street had happened only a couple of months earlier. His 60th in Cornwall was delightfully politics-free. As we tucked into the burgers he’d cooked on the BBQ, I thought this of my battle-companion: how amazingly unscarred you are by all those years we spent on the Westminster frontline. Seeing him surrounded by his old friends and listening to Sam’s loving speech, you’d have barely known he’d ever been PM. My presence was about the only giveaway. But that’s the exception that proves the rule. After all, what ex-prime minister has ever asked their chancellor to their birthday? I doubt Gordon gets an invite. Or Kwasi.

I welcomed the current Chancellor to the opening of the new Korea exhibition at the BM. All credit to him for coming with his Budget looming. My feelings when I first held the red box up outside No. 11 were a mix of exhilaration, nerves and relief that I didn’t drop it. I’d had a row with the National Archives in the run-up. They said I couldn’t use the famous Gladstone box that every chancellor since, except Gordon and Jim Callaghan, had used to transport their Budget speech to the Commons. It was fine for chancellors Lloyd George, Churchill, Lawson and Darling, but apparently young chancellor Osborne risked damaging it. I was incensed until our smooth-operating permanent secretary sorted out a deal: I’d use it on this first Budget and then for later ones we’d get a new one made. But when the day came, there was a problem. No one could find the key to open it. So I stood there in front of a bank of cameras holding up an empty box. This was our big Emergency Budget that cut spending, raised the pension age and increased VAT to get the public finances under control and yet also cut business tax and raised the personal allowance. My advice for next week? Better an empty Budget box than an empty Budget, John.

The leader of the opposition has to deliver the instant Budget reply. It’s technically difficult to pull off, but Kemi Badenoch did a good job last year. This year she’s buoyed by her performance at the party conference – the other star of which was not a member of her shadow cabinet but a Bayeux-style tapestry depicting Burnham’s seizure of the crown. She wrote to me saying she hoped I thought it was a fitting tribute to the real thing I’d showed her. I do. And now her office has sent Ed Balls and me two of their tapestry mugs. We’ll use them on our Political Currency Budget podcast next Wednesday. I’ve always thought the real tell that a party is getting its act together is whether they’ve got the self-confident sharpness to pull off funny stunts. Think of New Labour putting Thatcher’s hair on William Hague, or Cameron’s team handing out ‘Bottler Brown’ beers. Kemi’s Birmingham Tapestry more than passes my test.

I’ve just read Embargo, the new book from my friend and top writer Philip Delves Broughton. It’s a clever, fast-paced account of the 1973 Middle East war and the resulting oil price shock that pushed the world economy into a slump and sent a Labour chancellor off to the IMF for a loan. Now I write this diary in a Berlin anxiously re-arming, on my way to a Paris dousing the flames, as Britain dispatches jets to Saudi Arabia, while oil goes up and the bond markets get ready to mark the Budget of another chancellor called Healey. Just like Maya’s dress, the warning lights are red.