Note that I am not a professional reviewer or screenwriter, but here goes:
Your action and environment description are at times uneconomic and full of passive tense.
The thing is to "show, don't tell", in a way that is happening right now as "we see it".
So in your opening scene, things like "an important speech
" is not very relevant in the script. If it is important, show us how it is important! Then again I would assume all of the Queen's speeches are important?
Look out for this throughout your script; economy and active tense.
Her speech is quite long, so it's good you've added paragraphs. However, do we really see the Queen all this time she says this part? You could break it up with some action, like this:
EXT. THE BUCKINGHAM PALACE - DAY
A summer breeze gently fondles the Union Jack.
THE QUEEN speaks to a crowd below from her balcony. She is surrounded by her family; PRINCE PHILLIP, PRINCE CHARLES, PRINCE WILLIAM and PRINCE HARRY.
Her voice is soft, calm and well spoken.
... (her speech)
The crowd is divided by royalists and protesters. Each group holds banners, signs and placards against and for a "high speed rail".
THE QUEEN (CONT'D)
(... the rest of her speech)
Some formatting stuff, like scene headers, on a couple of places you do:
INT. BALCONY ROOM, DAY
You should do:
INT. BALCONY ROOM - DAY
(which is okay in most places but a few)
I would avoid capitalization (and underlining, bolding etc.) as much as possible. Let the director and in particular the actors (doing the voices) figure out the best way to emphasize their lines, unless it is something really
important to the story.
Direction in the script:
Don't do it if you plan to submit it somewhere. For example:
As The Queen continues to talk, the camera cuts to under the
table where Kate begins to rub Harry’s foot in a seductive
Could be rewritten as:
Under the table, Kate's foot reaches Harry’s and starts to rub it seductively.
As The Queen continues Harry is trying to escape Kate’s
Harry tries to escape Kate’s flirtatious foot.
In the dialog, a butler say:
Excuse me mam, but your guests have
arrived. Mr Cameron and Mr Clegg
are waiting downstairs in your
Wouldn't he address by title? "The Prime Minister and (...)
Music score may require licensing, so suggest - don't tell - the music as far as possible. (With regards to "The song ’Fleetwood Mac - Everywhere’ plays.
"). You do this i a good way in other parts of your script.
This scene was strange:
INT. PRINCE CHARLES’ BEDROOM - DAY
A sign hangs which shows that this is Prince Charles’
bedroom. The view is of(...)
Are we outside the room, and we are only supposed to hear Charles' and Camilla´s voices? Or are we inside the room to see the action? It doesn't make sense to me to have a sign on the inside of the door.
In the next scene I'm not sure your introduction of Mrs. Thatcher is OK. I'm missing a description of her appearance.
And in her last dialog lines of this scene, I'd splice the action in as it happens, not describe it afterwards. (The eye, and the picture of SJP).
EXT. POLITICAL RALLY - DAY
Cut to shot of GORDON BROWN standing behind a podium
Skip the "Cut to shot of" as the new scene header implies a cut anyway. And remember the active tense! GORDON BROWN stands behind...
(to KEN LIVINGSTONE)
Don't uppercase words there.
After the END MONTAGE
, of the epic battle between Ken and Thatcher, where are we?
Below the balcony? Or still on the balcony looking down on the protesters below? It is a bit unclear to me.
You wrote this:
Cut to shot of the men working happily in the mines,
chipping away at the black walls.
Cut the "Cut to shot" (you have this in many places), use active tense (this too occurs on many places) and set this particular scene up with a new scene header, as it is in a completely different location.
PRINCE CHARLES & PRINCE HARRY
We’re sorry. It won’t happen again.
There is actually a syntax for expressing this simultaneously. Split it up, remove the parenthetical, mark the two dialog paragraphs and press the "Dual dialog"-button in Celtx. I hope this made sense, since it's much easier to show than explain in words
The camera zooms in The Queen’s face to reveal her sadistic
and twisted smile. Dramatic and evil musics plays at it
The dramatic and evil music could play from the beginning of the scene, or just at the end? Remember, for a comedic/absurd effect, at times it can be useful to do the opposite, in this case use merry music. It's just an idea.
Fade To Black.
That's a transition, so format it properly (ctrl- or cmd+6) with: FADE OUT. appearing to the right.
As for the story, this is clearly for adults, and teenagers staying up late (depending upon channel, perhaps). For what it's worth, I liked it!
As a non-UK citizen, and non-native English speaker, there are some abbreviations and character descriptions you take for granted will be understood. This may probably work just fine in the UK, but if you intend for this to work elsewhere you may need to think about that.
The script felt a bit too long. If the rule of thumb "1 page per minute" holds, it would be a 46 minute animation. Aimed for television(?) I have no idea if this is optimal (or relevant).