THE DIARY, ARABELLA WEIR: Think it looks big? Don't mention it...

This is my first week owning a mobile and it's that old pathetic truth that I just can't imagine how I lived without it. I've even started doing something I hate. Talking on the train. I hate to admit I did a telephone interview throughout the entire journey from London to Nottingham.

I'm in the Midlands because I've started filming my new TV show She's Gotta Have It. It involves visiting about 94 different shops searching for clothes, and racing around like a fashion version of Challenge Anneka. In one store a woman comes up to me and says: "I'm sorry, I just bumped into you and I didn't say sorry. And I would never of done that if I'd realised who you were. I love everything you've done." Too right, we international celebrities must never be bumped into. Another man yells out: "I love you, I love the show." As this is the first SGHI I've done, he must think I am the previous presenter, Lisa Tarbuck. So much for international stardom.

Through all of this I have my four-month son in tow. I'm breast-feeding him, but the film crew are awfully sweet about everything. The whole show is timed to fit in with his feeds and every three hours they stop me and say: "It's time for Archie to eat now."

I'VE SPENT the day desperately trying not to mention my bum, which is difficult because most people know me because of my last book, Does My Bum Look Big in This?. But I've vowed to leave it behind me, where it belongs. Unfortunately one of the contributors (ladies having a makeover) spends the whole time worrying about the size of hers, constantly asking: "Does my bum look big in this?" and I have to reply: "I'm sorry I can't answer that question". I had less luck with my vocabulary on This Morning with Richard and Judy. I managed to say "cock" when discussing the show. The last time I was on I managed to say "arse", so it looks like I'm going for the hat-trick.

THE LAUNCH of my new book, Onwards and Upwards, at my old school on Wednesday is just like an old girls' reunion. I've got very fond memories of Camden School for Girls and I've kept a lot of friends. Lots of my old mates are there as well as my headmaster, but because it is a launch we have to be a bit more formal.

My male friends find it terribly exciting as the school have dressed up some Camden schoolgirls in our original 1970s uniforms and got them to serve drinks and canapes. The girls are classically lairy and self- confident in the way that Camden girls always are. My girlfriends are no different. It's one of the fantastic things about female relationships that you stay being as immature with your mates as you were the day you met - you don't have intellectual discussions, you just gossip about men, primarily.

IT'S BEEN such a busy week I'm beginning to feel a bit like a New York lawyer. I've spend a lot of quality time with my children: precisely five minutes every night. I was meant to get away early from filming today to see my daughter, but we had a bit of a drama. Two of the contributors wobbled out in tears and decided the whole thing was far too stressful.

The poor things had obviously been deceived by the glamorous image of television. "It'll be a lovely day out, trying on clothes and having a nice man doing your make-up." But the reality is lots of hanging about, crashing boredom, people popping out of nowhere to powder your nose and sticking their hands up your skirt to hoick it down. In the end they both did it and were both great sports. But I didn't get to see my daughter. It's getting really hard to be away from her all day. I worry that I might be ruining her life by going on location. But whatever you do, you know there's going to be a time when they grow up and start screaming that you've made their life hell.

MY RELATIONSHIP with my own mother has certainly been difficult. She was not of the Fairy Liquid variety and would come down to breakfast wearing a kaftan, smoking a joint and swearing like a trooper. My friends thought it was great but I wanted a "normal" mum. Last week I wrote a newspaper article about her. On reflection I'm worried the piece was a little too exposing.

I have mixed feelings about my upbringing. On the one hand, I feel it's my childhood and I'm entitled to remember it the way I remember it. But on the other, I also have a duty to be true to the good relationship I now have with both my parents. Today my mother really is my friend and confidante and I hope I was able to reflect that. Luckily, both my parents are sanguine and have a great sense of humour.

IN MY one leisure moment, I decide I'd like to see a celebrity Who Wants To Be A Millionaire? - where Chris Tarrant donates his fee. People could phone in and nominate a celebrity and the makers, Celador, could donate all the money raised to charity. Obviously it wouldn't work having celebrities who earn millions a year. Ainsley Harriot going "Ooh, I've won pounds 8,000 and I'm really excited" won't wash. Not that I'm nominating myself - I'd never get beyond 400 quid. Think I'll stick to doing telly and books.