"Fat lips would be all right," Shazzer said, "but not..." lowering her voice to a disgusted whisper ". . . fat labia." Ugh. Sometimes Shazzer is completely disgusting.

Right. Got to go. Am meeting Magda in Marks & Sparks at 6.30.

9 p.m. Back home. Shopping experience was perhaps best described as educational. Magda insisted on waving ghastly huge scary pants at me. "Come on, Bridget: the New Corsetry! Think 70s, think Cross Your Heart, think girdle," she said, holding up a sort of Cyclist Serial Killer's outfit in black Lycra with shorts, boning and a sturdy bra.

"I'm not wearing that," I hissed out of the corner of my mouth. "Put it back."

"Why not?"

"What if someone, you know, feels it"'

"Honestly, Bridget. Underwear is there to do a job. If you're wearing a sleek little dress or a pair of trousers for work, say - you want to create a smooth line. Nobody's going to feel you at work, are they?"

"Well, they might," I said defensively, thinking about what used to happen in the lift at work when I was 'going out' - if one can describe that commitment-phobicity nightmare as such - with Daniel Cleaver.

"What about these?" I said hopefully, holding up a gorgeous set that was made out of the same material as sheer black stockings only bra and pants shaped.

"No No! Totally 1980s. This is what you want," she said, waving something that looked like one of Mum's roll-ons crossed with her long johns.

"But what if someone puts their hand up your skirt?" "Bridget, you are unbelievable," she said loudly. "Do you get up every morning with the idea that some man might randomly put his hand up your skirt during the course of the day? Don't you have any control over your sexual destiny?"

"Yes I do actually," I said defiantly, marching towards the changing room with a whole handful of sturdy pants. Ended up trying to squeeze myself into a black rubberlike sheath, which came up to just below my breasts and kept unravelling itself from both ends like an unruly condom. "What if Mark sees me in it or feels it?"

"You're not going to smooch in a club. You're going to a formal dinner where he'll be making an impression on his colleagues. He'll be concentrating on that - not trying to grope you."

Not sure Mark ever concentrates on making an impression on anyone actually, as is confident in self. But Magda is right about the underwear. One must move with the times, not becoming entrenched in narrow underwear concepts.

Right, must get early night. Gym appointment is at 8 in morning. Actually really think whole personality is undergoing seismic change.

Friday 31 January: D-Day

9st 4, alcohol units 6 (2)*, cigarettes 12 (0), calories 4,284 (1,500), lies told to fitness assessor (14).

*Figures in brackets denote data given to fitness assessor.

9.30 a.m. It is typical of the new louche health club culture that personal trainers are allowed to behave like doctors without any sort of Hippocratic oath.

"How many alcohol units do you drink a week?" said 'Rebel': Brad Pitt-style whippersnapper fitness assessor as I sat trying to hold in stomach in bra and pants.

"Fourteen to twenty-one," I lied smoothly, at which he had the nerve to flinch.

"And do you smoke?" "I've given up," I purred.

At this, Rebel glanced pointedly into my bag where, OK, there was a packet of Silk Cut Ultra, but so?

"When did you give up?" he said primly, typing something into the computer that would obviously go straight to Conservative Central Office and ensure I am sent to a boot camp next time I get a parking fine.

"Today," I said firmly.

Ended up standing having fat measured with pinchers by Rebel.

"Now I'm just making these marks so I can see what I'm measuring," he said bossily, putting circles and crosses all over me with a felt tip. "They'll come off if you rub them with a bit of white spirit."

Next had to go into gym and do exercises with all sorts of unexplained eye contact and touching with Rebel - e.g. standing opposite with hands on each other's shoulders with Rebel doing squats, bouncing bottom robustly on mat and me making awkward attempts to bend knees slightly, At end of whole thing felt as though had had long and intimate sex session with Rebel and we were practically going out. Afterwards got dressed and had shower then was unsure what to do - seemed ought at least to go back in and ask what time he'd be home for dinner. But of course am having dinner with Mark Darcy.

V. excited about dinner. Have been practising in outfit and really it looks excellent, sleek smooth lines, all thanks to scary pants, which there is no reason he should find out about. Also really no reason why should not be v.g. escort. Am woman of world with career etc.

Midnight. When finally arrived at Guildhall, Mark was pacing up and down outside in black tie and big overcoat. Fwaw. Love when you are going out with someone and they suddenly seem like an extremely attractive stranger and all you want to do is rush home and shag them senseless as if you have only just met. (Not, of course, that that is what normally do with people have only just met.) When he saw me he looked really shocked, laughed, then composed his features and gestured me towards the doors in polite, public-school fashion.

"Sorry I'm late," I said breathlessly.

"You're not," he said, "I lied about the kick-off." He looked at me again in a strange way.

What?" I said.

"Nothing, nothing," he said over-calmly and pleasantly, as if I were a lunatic standing on a car holding an axe in one hand and his wife's head in the other. He ushered me through the door, as a uniformed footman held it open for us.

Inside was high, dark-panelled entrance hall with many black-tied old people murmuring around. Saw woman in sequinned crusty top thing looking at me in odd way, Mark nodded pleasantly at her and whispered in my ear, "Why don't you just slip into the cloakroom and look at your face."

I shot off into loo. Unfortunately, in the dark of taxi, I had applied dark grey Mac eyeshadow to my cheeks instead of blusher: the sort of thing that could happen to anyone, obviously, as packaging identical. When came out of toilets, neatly scrubbed with coat handed in, stopped dead in tracks. Mark was talking to Rebecca.

She was wearing a coffee-coloured plunging, backless satin number that clung to her every fleshless bone with clearly no corset. Felt like my dad did when he put a cake into the Grafton Underwood fete and when he returned to it after the judging it had a note on saying, 'Not up to Competition Standard'.

"I mean it was just too funny," Rebecca was saying and laughing full in Mark's face affectionately. "Oh Bridget," Rebecca said, as I joined them. "How are you, lovely girl!" She kissed me at which could not stop self pulling face. "Feeling nervous?"

"Nervous?" said Mark. "Why would she be nervous? She's the embodiment of inner poise, aren't you, Bridge." For just a split second saw a look of annoyance cross

Rebecca's face before she composed it again and said, "Ahhh, isn't that sweet? I'm so happy for you!" Then she glided off with a coy little backwards look at Mark.

"She seems very nice," said Mark. "Always seems extremely nice and intelligent."

Always?? I was thinking. Always? I thought he'd only met her twice. He slid his arm dangerously close to my corset so had to jump away. A couple of huffer-puffers came up to us and started congratulating Mark about something he'd done with a Mexican. He chatted pleasantly for a minute or two then skilfully extracted us, and led us through to the dining room.

Was v. glamorous: dark wood, round tables, candlelight and shimmering crystal. Trouble was, kept having to jump away from Mark every time he put his hand on my waist.

Our table was already filling up with an array of brittly confident thirty-something lawyers, bellowing with laughter and trying to outdo each other with the sort of flippant conversational sallies that are obviously tips of huge icebergs of legal and Zeitgeisty knowledge: