James Naughtie once did Today in his dinner jacket, his day kit being locked in St Paul's Cathedral

With only a couple of weeks to go before I leave Today, I still haven't quite grasped the huge significance of what I'm about to do. Depart from BBC Radio's flagship news programme! Leave daily live broadcasting after almost four decades! When all the latest surveys show Today is more popular, more listened-to than ever! I must be mad.

I've been totting up all the things I'll miss. Not just my early-morning colleagues John and Jim and the (usually) cheerful, toiling team behind them, but our huge, messy, open-plan office, the unwelcome move to which three summers ago I chronicled on these pages, with its rows of glowing computers and piles of newspapers, press releases and old copies of the Nursing Times, and the coffee machine that makes passable instant cappuccino. I shall not for one second yearn for the 3am alarm call, or talking to scientists at 4am about cloning. But I shall certainly think back longingly to office jokes, great gossip and a chance to grill important people about the way the world turns.

Presenters of Today also get invited to interesting parties and other happenings after hours. At least 50 per cent of them have to be turned down, by me at least, because they mean getting to bed too late. Yet now that I'll be free to go to as many good bashes as I like, the invitations will almost certainly dwindle, like autumn leaves, to a precious few. Shame.

Channel 4 and The House magazine dished out their political awards last Wednesday, but, luckily for me, it was at lunchtime. Over the pre-prandial snacks, I spied William Hague and Barbara Castle having what the gossip columnists call an "animated conversation", and longed to suggest to one of the operators of the dangling roving microphones that they dip in to eavesdrop. It was interesting to observe how many of the candidates for awards seemed to have discreetly applied just a little extra layer of make-up - even the women. Later, Baroness Castle - sparky as ever, though in her nineties - gave the special House award to Clare Short. This involved a rather testing clamber on to the platform, which Barbara managed magnificently, and another one down again, over which she was heard to mutter something. Jon Snow, the man in charge, enlightened the audience. "She's just said: 'They're all waiting for me to fall a**e over t*t!'" David Owen, sitting next to me, revealed that his time working as a junior minister under Barbara had been one of the most enjoyable of his political life.

One of my first jobs as a junior reporter for the World at One was to record an interview with her about introducing car seat belts - at the time a controversial proposal. It was her responsibility to persuade her opponents and the nation that belting up was a good idea, just as it subsequently became Maggie Thatcher's to announce that free school milk was no longer a universal right. No coincidence that they were both rare women in their respective cabinets. As one political correspondent told me: "They always give the women the worst jobs."

My imminent departure from Today has also coincided with the publication of my autobiographical book, long extracts from which have appeared in the Daily Mail. Anyone who persevered with the serialisation beyond the first revelations, or, indeed, read the book itself, will have discovered, I hope, that there's rather more to it than an account of one or two love affairs, though that section produced the predictable cries of horror. As a brand new author, I tiptoed nervously into my local branch of a bookselling chain on publication day to see if they had any copies, and how prominently they were displayed. And there - oh, heavens! - was a great pile of them downstairs in Biography, next to Posh Spice and Roy Jenkins's magnificent Churchill. Out of the corner of my eye, I saw a young couple approaching. I backed away. As I cautiously turned round at the foot of the stair, the man picked up my book. "Oh, look . . . " he said. What else did he say? Did he buy it? I've no idea. I fled. I expect a more seasoned author would have lingered and even got into conversation, or pulled the whole pile into a more prominent position. I'm sure I'll learn the tricks of the trade.

I dare say it would have been unthinkable for a woman broadcaster to reveal anything about her private life when I first worked for the dear old Beeb as a very junior freelance reporter 35 years ago. The corporation was run very much on civil service lines, with unbreakable rules about going public, and carefully graded perks. Programme producers grand enough to have their own offices got soap, a clean towel, a better-quality carpet and a man who came and disinfected the telephone once a week. Lesser mortals who did shopping in their lunch hour and carried stuff in plastic bags through Broadcasting House's front reception were bawled out for inappropriate behaviour. Everyone was expected to dress as if for a job interview.

One office I worked in had a hat for the female staff for last-minute grand occasions, like an invitation to a royal garden party. Now the only suits are the invisible men behind closed doors. (Though Jim Naughtie did once present Today in his dinner jacket. It was nothing to do with the old Reithian rules about how to dress when reading the nine o'clock news on the Home Service; someone had locked away his day kit late at night in St Paul's Cathedral. I fear it's really too complicated to explain the whys and wherefores . . . )

But after the initial reaction to my book, perhaps an armadillo skin would be a handy carapace for novice authors. Anyone know any going cheap?