I’m trying to do a seating plan, but honestly, it’s worse than Sudoku, and I’m too preoccupied to concentrate. Janice keeps coming in and fussing about where exactly the marquee entrance will be, and Minnie jams a pencil in the DVD player halfway through Finding Nemo. So basically it’s five o’clock and I haven’t got beyond table three when there’s the sound of a key in the front door. Hastily I gather up my table charts and shove them in the cupboard behind Dad’s Sounds of the Seventies CD collection. When Luke comes in, I’m sitting on the sofa, reading a book which I’ve just grabbed off the floor.

‘Hi, how was it?’ I look up.

‘Great. Really good.’ Luke is glowing even more triumphantly than he was this morning. ‘Sir Bernard’s a great guy. He was on side, wanting to listen, interested. We raised a lot of thought-provoking side issues …’

‘Fantastic!’ I smile – but I can’t quite relax yet. I have to be sure. ‘So … you definitely won’t need to go to Paris on Friday?’

‘Afraid not. Although we could still go if you wanted?’ Luke adds.

‘No!’ Relief sends my voice shooting sky-high. ‘God, no! Let’s just … stay here. Chill out. Not do anything.’ I’m babbling, but I can’t help it. ‘So, a good day all round.’ I beam at him. ‘We should open some champagne.’

‘Yes. Apart from one thing.’ Luke frowns briefly. ‘I had to give my assistant a verbal warning. Not really the way I wanted to end the afternoon. I may have to let her go.’

What? My smile falls away.

‘You mean Bonnie? But … why? You said you wouldn’t say anything. What did she do?’

‘Oh, it’s very disappointing.’ Luke sighs. ‘For months she seemed the perfect assistant. I couldn’t fault her. But then she started making the inappropriate comments that I mentioned to you before. I’ve recently noticed she seems very distracted. And now I’m sure she’s been making illicit phone calls of some kind.’

Oh God, oh God. This is all because of me and the party.

‘Everyone’s allowed to make the odd phone call,’ I say quickly, but Luke shakes his head.

‘It’s more than that. I have my suspicions. At best she’s moonlighting; at worst, stealing company information.’

‘She wouldn’t do anything like that!’ I say in horror. ‘I’ve met her. She’s obviously completely honest.’

‘Darling, you’re very trusting.’ Luke shoots me a fond smile. ‘But I’m afraid you’re wrong. Something’s going on. I came across Bonnie dealing with a pile of paperwork that quite clearly had nothing to do with Brandon Communications. Not only that, she looked as guilty as sin when I appeared and she hid some papers under the desk. She obviously didn’t expect me back for a while. So I had to have a stern word.’ He shrugs. ‘Not pleasant for either of us, but there you go.’

‘You were stern?’ I say in horror.

I can just picture what happened. Bonnie was going through the guest list with me this afternoon. That must be what she hid under the desk. I thought she rang off rather hastily.

‘What exactly did you say?’ I demand. ‘Did she get upset?’

‘Does it matter?’

‘Yes!’ I feel a surge of frustration. You stupid idiot! I feel like yelling. Did it never occur to you that she might be helping to organize your surprise birthday party?

I mean, obviously I’m glad it didn’t occur to him. But still. I just hope Bonnie’s OK. She’s so mild-mannered and sweet, I can’t bear the idea of Luke upsetting her.

‘Becky …’ Luke seems perplexed. ‘What’s the problem?’

I can’t say anything else. I’ll give myself away.

‘Nothing.’ I shake my head. ‘No problem. I’m sure you were right. It’s just … a shame.’

‘OK,’ Luke says slowly, giving me a slightly odd look. ‘Well, I’ll go and change. Nanny Sue will be here before too long.’

The instant he’s gone, I dash into the downstairs cloakroom, speed-dial Bonnie’s number, and get voicemail.

‘Bonnie!’ I exclaim. ‘Luke just told me he gave you some kind of verbal warning. I’m so sorry. You know he doesn’t understand. He’ll feel terrible when he finds out. Anyway, the good news is, Paris is definitely off! So everything’s finally falling into place. Have you told all the Brandon C lot yet? Call me as soon as you have a chance.’

As I ring off, I hear the doorbell.