We might as well get this over with.

You've watched Ruth Davidson chin Boris Johnson on national television and you reckon, "Hey, she could be a good shout for Prime Minister, or at least Tory leader."

Ah, you remember, but she's something high up in that Scottish Parliament thingy. Surely she'd come down south for a safe seat and a chance at the top job.

Afraid not.

After pulling off a stunning result in May's Holyrood election, more than doubling the Tories' seats and replacing Labour as the official opposition, Davidson already has an important job. She is the one who has to hold the SNP to account, not an easy task given its near-complete dominance of Scottish public life and anaphylactic reaction to any criticism.

Of course, Number 10 is where all ambitious and talented politicos dream of ending up but Davidson is a Unionist first and her top priority is glueing the Union back together after Alex Salmond took a sledgehammer to it. Independence is still on the table and if we Brexit against Scotland's will on Thursday, the clamour for Jockxit will be deafening. To win Downing Street but lose your country isn't much of a step up in the round.

That's why it's a touch patronising to hear Westminster commentators describe her as "the future of British politics". She's not the future, she's the present. (She has also force-fed various foodstuffs to BuzzFeed Scotland correspondent Jamie Ross. There's no way that wouldn't end up on a Labour poster in 2020.)

Her abilities were on display for all to see in Tuesday night's EU debate from Wembley Arena. Chaired by David Dimbleby before an audience, half of whom applauded every time someone on their side took a sip of water, the programme pitted three figures from each campaign.

Ruth Davidson, Sadiq Khan, and Frances O'Grady, for Britain Stronger in Europe, and Boris Johnson, Mum and Grandmother Gisela Stuart, and Andrea Leadsom, also understood to have birthed progeny who have gone on to conceive offspring of their own, for the official Leave campaign, Immigrants Are Coming To Get Your Children.

The Leavers knew their strong points and hammered them mercilessly. Immigration. Turkey. Unelected Brussels bureaucrats. (While I have you, don't forget to register for next month's civil service elections.) For Remain, the challenge was to debunk the crude demagoguery of the Brexiteers. As Khan put it, their job wasn't to be "Project Fear" but to take on "Project Hate".

But the debate that mattered was between Johnson and Davidson, two starkly contrasting symbols of modern conservatism -- the scion of privilege versus the blue collar girl from Fife. She thrashed Boris worse than an Eton prefect. That faux-bumbling bluster might impress Sloaney features writers and Have I Got News For You viewers but Davidson was deliciously impatient with the blond-tousled bounder.

The Leave campaign has profited from having a go at Turkey -- if this Brexit business doesn't work out, they should set up a Westminster branch of the PKK -- and they blew the dog whistle time and again on Tuesday night.

Ruth Davidson came prepared, though. Turkish membership of the EU was "simply not going to happen. It's not on the cards". Not her words; those of Boris Johnson on LBC radio two months ago.

She used his loose tongue against him again on the issue of employment, where Johnson has blithely admitted jobs "might or might not" go. "They might or they might not?" Davidson demanded, with genuine anger. "That is not good enough. How many jobs would go, Boris? How many would go?"

The best he could muster was a whine about "Project Fear".

Having booted him a good few times, Davidson went for a slug in the gut.

"Boris, can you name me just one country in the world that has said it will give us a better deal if we come out of the EU?"

Answer came there none.

Boris wasn't the only separatist on the receiving end of a Ruthing. She accused her Tory colleague Andrea Leadsom of lying about how many laws and regulations affecting the UK originate in Brussels. "That is a lie, that is a straight-faced lie and you are better than that," Davidson shouted over her.

And when Gisela Stuart -- official sponsor: Mumsnet -- tried her motherhood and apple pie routine yet again, Davidson called a halt to the family affair: "I have to remind people at home there are mums and dads and grans and granddads on this side of the debate as well."

On Britain's role in the world, Davidson was able to use her service in the Territorial Army to pull rank on the Brexiteers, desperate to avoid the security implications of leaving the EU.

Davidson dominated at all the key moments, hounding the nationalists on their dodgy claims. Unlike part-time Remain campaigner Nicola Sturgeon, Davidson put in a proper shift in her TV debate.

Her closing statement was powerfully delivered and could well have chimed with undecided voters. She told the arena audience: "You are being asked to make a decision that is irreversible, we can't change if we wake up and we don't like it and we are being sold it on a lie. They lied about the costs of Europe, they lied about Turkey's entrance to Europe, they lied about the European army -- we have got a veto over that. They put these in their leaflets and they have lied here about this too. It's not good enough. You deserve the truth."

It was one of the most important speeches of her life. It might have helped shift enough votes to avert disaster tomorrow.

So no, England, you can't have Ruth Davidson. Scottish politics needs her to maintain a healthy, adversarial democracy north of the border. But if you like what you saw last night, you might want to look at the line-up of rumoured replacements for David Cameron and ask: "Is this really the best we can do?"

Maybe it's time to take control of your politics instead of just talking about it.

Comment by Stephen Daisley, STV's digital politics and comment editor. You can contact him at stephen.daisley@stv.tv.