-May contain spoilers-

Since I first saw it, I have liked the movie Nanny McPhee (2005), the character of Simon Brown (Thomas Sangster) in particular. But I have never tried to puzzle him out, for the simple reasons that 1) I’m not in the habit of doing organized character analysis, and 2) Nanny McPhee is a children’s movie. What more could there be than the surface?
But now that I’m floating there anyway, I’m going to see how far I can wade. Let’s take a look at the surface.
At the start of the mvoie, the narrating voice of the father, Mr. Brown (Colin Firth), sums if up fairly: "[They were] all very clever, but very, very, very naughty." Indeed, the first time we see Simon, he is eating his youngest sister’s leg. It’s actually a chicken leg in a pink bootie, meant to scare away their seventeenth nanny. They succeed, and in his second scene with lines he slyly celebrates the lack of replacement nannies. His first lines record how fast they got rid of her and her predecessors. We have just learned that Simon is the mastermind among the seven Brown children. And he likes it.
The naughty part of the opening line makes the movie. It occurred to me that, like the children in Sound of Music, Simon and the other Brown children could merely be trying to get their father’s attention with their tricks. However, to say "merely" may be an understatement.
A point of interest is the game of Monkey See, Monkey Do the Brown children play in the kitchen, and again when Aunt Adelaide visits. Simon takes the lead when he pretends not to see Nanny McPhee (Emma Thompson) and he suggests putting his best clothes on the pig. His siblings promptly follow suit.
How did Simon come to be their undeniable leader? We aren’t told, but I can imagine what happened: Mama was dead; Papa was growing detached and distracted to the point where they believe "Fathers all turn bad once their wives die. They don’t care anymore." To whom could they turn? Their eldest brother was born for the role: one of them, a leader, and, as is said so many times, very clever. Movie website www.nannymcphee.com says in the production notes: "’Simon is the team leader, so he rounds them all up and thinks up all the naughty ideas,' explains the 15-year-old actor [Thomas Sangster]. 'He is also very separate from all the other children, who are all younger than him. He looks after them, but behind everything he’s actually quite sad.’"
Simon’s initial reaction to Nanny McPhee is probably his reaction to the other nannies: indifference toward authority and a deep sense of mischief at her expense. By the end of the first night, he’s said "please" to save his sister’s life, but he’s scarcely skipped a beat. He’s not ready to surrender command, certain his family can outsmart her yet.
But he soon learns, in fact, that they can’t; even on her holiday she saves their hides (almost literally). And, in a moment of lovely vulnerability, Simon thanks her from his heart.
From the latter scene, we learn how much having his family together means to Simon, a love probably strengthened by his mother’s death. Family, not play, is everything to Simon. In addition, as he and the other children begin to trust Nanny McPhee, he almost sees her as one of that troupe.
"You saved [his sister] Chrissie. And so… You're on our side, is what I mean," he stammers. "Aren't you?"
She replies, "You saved Chrissie, and I do not take sides."
Simon leads his siblings to sabotage the visit of a horrid woman, but discovers his family will be separated because of it. He is not only horrified and repentant but terribly frightened. He is desperate to fix things—even at the cost of laying down his pride and begging to and for what he dreads most: his "new mummy."
For the sake of not spoiling more than necessary, I’ll just leave my point at that.
We viewers get few glances into the lives of the Brown family before Mrs. Brown’s death. We infer she spoiled her children ("If ever they were ill, she used to wait on them hand and foot... even if they weren't very ill at all," Mr. Brown tells Nanny McPhee). This may be the root of the lack of respect for authority in the children. Yet they and their father obviously love her very much.
Of Simon and Mr. Brown, the servant Evangeline (Kelly MacDonald) says, "You used to be as close as anything." It is mentioned that he used to read stories and sing lullabies to them, implying the bond they shared—and still could share, if they could salvage it.
I know this study has been rather rough, but keep in my that my first try was constantly distracted rambling. So here’s my conclusion:
I wish the movie hadn’t ended. I wish it could be a book. I want to follow Nanny McPhee down the road and see where she takes me. But more than that, I want to follow these seven children to adulthood. I want to know how they grow up and turn out. I want to see Simon at twenty-five—he’s interesting now; I’m certain he’d be magnificent then.
It all comes of getting a fifteen-year-old to play a twelve-year-old.