INT. GORDON BROWN'S OFFICE - DAY
Jacqui & Gordon sit, discussing matters.
JACQUI
Gordon, I'm not happy!
GORDON
Yes, I know.
JACQUI
I simply must have 42! Anything less than that is just not on.
GORDON
Well, I suppose you might try again. But some people think 42 is dangerous.
JACQUI
That's rubbish. I'm going to try again, I just couldn't show my face in parliament with anything less.
GORDON
Very well. You're bound to find a cosmetic surgeon somewhere who can do breast implants that large.
I like the rhythmn of this and it's not a bad idea, but hasn't Jaqui Smith got big tits already?
Ah, er, you may be right, not that I've ever looked, guv, honest. 
Maybe she's going to have them reduced to 42 instead!
I'd tie it into the governemnt banning free booze for ladies.
42% proof Vodka or 42 pints maybe?
Perhaps 42 should be used to in relation to something that would strike fear into any woman - age.
Think it's a very good idea of her being obsessed with getting 42. Think it's a decent sketch, though does feel like there's more potential in it.
Could be a nice runner, Jacqui Smith going out, hampered by her obsession.
e.g. Jacqui Smith playing Blackjack, getting 21, but wanting 42, or somesuch.
or as per your original, being measured for a bra, pushing out her chest trying to get the assistant to say 42.
or how about her briefing her fellow MPs in a schoolroom, they're messing about like schoolchildren, she threatens to put them in detention-some joke about her not being able to detain them for long...
When I read the post title, I thought it would be a Hitchhiker's Guide-related sketch, (i.e. 42 was the meaning of life, the universe and everything)-I actually rather like that idea.
I'm afraid I might not have been terribly helpful, but maybe you can do summat with the brainstorming.
Hi Rob0, thanks for reading it, it's nice to have people do that. I like the Blackjack gag.
I have to say I was partly inspired for this by a funny photo of Jacqui explaining some point, with her hands in front of her chest as if she were demonstrating how big she'd be after having enhancements! I will see if I can find it.
Happy to read it, was a good sketch and one of those great ideas that could be executed in a wide variety of ways.
If you do find the photo, could do a voice over to it, or, better, a video if there's a clip.