Some suggestions:

1. Experiment with aversion therapy. Attach electrodes to Basher’s ears, every time during rehearsals that he says “uhhm” or “errrr” flick the switch. His SAS training will mean he will be able to withstand the pain. This is still your only hope of getting him to stop stumbling and mumbling. Basher may think rhetoric is not important, but it seems a lack of rhetorical ability in modern politics only qualifies you for the office of deputy-PM. Aim for the top.
2. Tell him to stop laughing nervously at his own jokes. They are not funny and it makes people think he’s a wrong ‘un. Its also ruining his macho image.
3. Think about what questions will come up – clues: tax, cannabis, some quirky thing from the tabloids like Blunkett. If you prepare a jokey response, make sure he remembers (2)
4. Although its not only Tories who will be watching they will be the only ones voting, don’t let him come over all Northern and chippy, its southern Tories who have all the votes. Kensington and Chelsea Conservative Association has more votes than the whole of the North (approx).
5. The “Blair heir” thing – Blair wins elections and voters prefer him to Brown, they may also prefer his heir. Tricky admittedly, given even some Tories wish Blair was leading the Conservative party. Some of the older members get easily confused, they may mishear and think Cameron is Euan. Be careful.
6. The age issue – don’t call Cameron “son”. Basher mustn’t try to make out he has cabinet experience, shadow cabinet doesn’t count. Consider dying his hair / getting him a better toupee.
7. That Heineken analogy – nobody drinks Heineken anymore, its naff. We all smoke dope instead. Could he maybe be an Ipod candidate instead? Get one of the spin team to think of a more “with it” brand. Better still is he perhaps a Bacardi Breezer Geezer? He is the Vinny Jones of Tory politics and Vinny advertises Bacardi. Worth considering.
8. Careful on the tax cuts thing – Chatshow Charlie buggered it up completely when he couldn’t do his sums on local tax. Its probable that Brown’s wheels will have fallen off and the economy will be declining in three years time. So how would the growth rule work without growth?
9. Consider getting him to show his more human side – perhaps a novelty tie?
10. Don’t blame the media, its your own fault.