I’ve done my research. I’m taking this seriously. I’m going to be the best extra ever.

No, not ‘extra’. The proper term is ‘background actor’. I’ve found out so much on the internet about being an extra, I feel really well prepared. For example, you should always bring playing cards or a book in case you get bored. And you shouldn’t wear green, in case they’re using a green screen for CGI. And you should bring a variety of outfits. Although that doesn’t apply in this case, as apparently our costumes will be provided. A limo has also been provided to take us to the film set, which is definitely not standard practice. They’re being super-nice to us because of Suze being married to Tarkie.

In fact, I’m secretly hoping they might be so nice that they give us each a little line to say. I mean, why not? Obviously not big lines or speeches or anything. Just something small. I could say, ‘’Tis true, cap’n,’ after the Pirate Captain makes a speech. And Suze could say, ‘Land ahoy!’ or ‘Ship ahoy!’ or ‘Pirate ahoy!’ Anything ahoy, really. I’ve been practising a special growly, piratess voice in the mirror, and I’ve read an article on acting for film. It says the most common mistake, even for trained actors, is to over-act, and that the camera picks up the most infinitesimal movements and magnifies them, so you need to make everything tiny.

I’m not sure Suze realizes this, because she’s spent the whole of breakfast doing all these loud warm-up exercises and shaking her hands out to ‘loosen herself up’ and saying ‘Wibble-wobble’ over and over again. But I can’t tell her anything about acting, because she just says, ‘Bex, I went to drama school, remember.’

The film is being shot at a soundstage in Burbank, and that’s where we’re heading right now. Luke is dropping off Minnie at pre-school today, as well as Suze’s children. (As soon as the headmistress found out who Tarkie was, she fell over herself to offer the Cleath-Stuarts temporary places, and the principal of a nearby school immediately found space for Ernest too.) We’re sitting in the limo, watching the billboards speed by and grinning madly at each other. This is the most exciting thing I have done in my life, ever.

I don’t know what the scene’s about – in fact, I don’t really know what the film’s about because all it says online is ‘Drama set on the high seas’. But I’ve done a bit of practice at swinging a cutlass (I used a kitchen knife) because you never know, it might be a fight scene.

‘Hey, Suze, if I have to fight someone, bagsy it’s you,’ I say.

‘Me too,’ agrees Suze at once. ‘Except, will the womenfolk fight? They might just look on and jeer.’

‘There are female pirates,’ I say knowledgeably. ‘We can be one of those. Look at Elizabeth Swann.’

‘I want to fight Captain Jack Sparrow,’ says Suze longingly.

‘He’s not in it!’ I say for the millionth time. Suze is a bit hung up on Johnny Depp, and I think she was hoping that we were going to be in a new Pirates of the Caribbean. But it’s not that. It’s called The Black Flag, and I don’t recognize the names of any of the stars except April Tremont, who is playing ‘Gwennie’.

‘I know he’s not. But still. Wouldn’t it be amazing?’ She sighs.

‘There’ll probably be an even hotter pirate king in this one,’ I point out, as my phone rings. It’s Dad calling, which surprises me. Normally it’s Mum who rings, and then passes me over to Dad, and then instantly grabs the phone back as there’s something she’s forgotten to tell me about Janice’s new sofa covers or the geraniums.

‘Dad!’ I exclaim. ‘Guess what Suze and I are doing right now?’

‘Drinking orange juice in the sunshine,’ says Dad with a laugh. ‘I hope you are.’

‘Wrong! We’re in a limo, going to the film set!’

Mum and Dad already know we’re going to be extras in a movie, because I phoned them up to tell them, straight away. And Janice and Martin. And Jess and Tom, and my old bank manager Derek Smeath …

I suppose I did phone quite a few people, now I think about it.

‘Wonderful, darling!’ says Dad. ‘Make sure you hobnob with the movie stars.’

‘We will!’

‘I was just wondering, did you ever manage to look up my old friend Brent?’

Oh. Damn. What with Golden Peace, and Suze arriving, it completely slipped my mind.

‘Not yet,’ I say guiltily. ‘I haven’t quite had time. But I will, I promise.’

‘Well, that would be marvellous.’

‘I’ll go and see him really soon, and I’ll give him all your details.’

We’ve arrived at a barricaded entrance to a large complex with buildings and courtyards, and as the driver slows down, I see a row of trailers out of the window. Real film trailers!

‘We’re here! There are trailers!’ I say in excitement. ‘Oh Dad, you should see it!’

‘Sounds fantastic,’ says Dad. ‘Well, you let me know about Brent.’

‘I will,’ I say, only half paying attention. ‘See you, Dad.’

The driver is giving our names to the gate man. As Suze and I stare out of the window, agog, I see a man in a pirate costume walk to one of the trailers, knock on the door and go inside.

‘Oh my God,’ says Suze.

‘I know!’ I can’t help giggling.

As we’re whisked into the complex, my head is swivelling this way and that, trying to take in every detail. It’s all just as I imagined. There are girls with earpieces and clipboards. There’s a guy carrying what looks like a marble statue under his arm. There’s a woman in a crinoline, talking to a man in a leather jacket.

‘I’m nervous,’ says Suze suddenly. ‘What if I’m crap?’

‘Nervous?’ I say in astonishment. ‘Suze, you’ll be great!’ The car stops and I squeeze her arm encouragingly. ‘Come on, let’s go and find some coffee. You know, the main thing about being in a film is the catering.’

I’m so right about the catering. After wandering about for a few minutes we find this great big table called Craft Service, covered with a fabulous array of coffee, tea, biscuits, cupcakes and even little sushi rolls. As I’m eating my third cherry-almond cookie, a guy in a headset comes up, looking a little hassled.

‘Are you Lady Cleath-Stuart?’

‘Here,’ says Suze, her mouth full of muffin.

‘I’m Dino, the second AD. You were supposed to meet me out front.’

‘Oh, sorry. We wanted some coffee.’ Suze beams at him. ‘This hazelnut latte is delicious!’

‘Oh. Great.’ He mutters something into a tiny walkie-talkie, then looks up again. ‘Well, let me take you to meet Don. He’s our publicist and he’ll be looking after you today.’

Don is very dapper and has the strangest cheekbones I’ve ever seen. What has gone on with those? Has he had them filled? Or has he had his cheek fat sucked out? Either way, it hasn’t been a success, not that I’m going to mention this or stare at his face. Much. He ushers us into a massive warehouse-like space, and lowers his voice as we pick our way over wires and cables.

‘Lady Cleath-Stuart,’ he says with reverence, ‘we’re delighted to welcome you to the set of The Black Flag. We want today to be as enjoyable and interesting for you as possible. Please, follow me. We thought you’d like to see the set before we take you to Wardrobe.’

Suze is totally a VIP! This is so great! We both hurry after him, dodging past some guys carrying a fake stone wall made out of wood. We head towards a cluster of directors’ chairs and a monitor, and lots of people with headphones and serious expressions.

‘That’s what we call “video village”,’ Don says in an undertone. ‘This is where the director watches the action. Please make sure your phones are switched off. I think we’re about to have a take.’

We edge round until we can see the set properly. It’s the interior of a library, and two actors are sitting on armchairs. The lady is all dressed up in a velvet crinoline and the man is in a tailcoat. Bending down, talking to them intently, is a skinny guy in jeans with bright-red hair.

‘That’s Ant, the director,’ murmurs Don. As we’re watching, Ant leaps back to his chair, puts on his headphones and stares intently into his monitor.

‘Rolling!’ yells someone from the set.

‘Rolling!’ several other people echo at once. ‘Rolling! Rolling!’ Even behind us, by the door, two girls are yelling, ‘Rolling!’

‘Rolling!’ I join in helpfully. ‘ROLLING!’

This is so cool. I feel like a member of the film crew already!

‘Action!’ calls Ant, and, like magic, the whole place becomes totally still. Anyone who was walking has stopped dead, and all conversations have ceased, mid-sentence.

‘Kidnapped,’ says the lady in velvet. ‘Kidnapped!’ The man takes hold of her hand and she gazes at him mournfully.

‘Cut!’ shouts Ant, and leaps down on to the set again.

‘This scene is set in the home of Lady Violet,’ whispers Don. ‘She’s just learned that their daughter Katriona has been kidnapped by pirates. Would you like to go closer?’

We tiptoe forward, till we’re at ‘video village’. There are several directors’ chairs with names printed on the backs of them and I look at them lustfully. I would die to have a chair with my name on it. My mind is suddenly seized with an image of a chair reading: Becky Brandon, Wardrobe Designer. Just imagine if I started working in movies and I got my name on the back of a chair! I wouldn’t ever want to stand up. I’d walk around with my chair stapled to me.

The wardrobe designer on this movie is called Renée Slattery. I’ve already Googled her and planned what I’ll say if we meet. I’ll compliment the costumes in Saw Her Too Soon, which is another movie she worked on, and then I’ll talk about the challenges of working with period dress. (I don’t know much about that, but I can busk it.) And then I’ll ask casually if she needs any help, maybe with shopping for grosgrain ribbon, or button boots, or whatever.