The revelation that David Cameron texted Rebekah Brooks at the height of the hacking scandal to "keep her head up" reduces us all to paranoid parents checking the inboxes of our teenager's phones. We just want to know that they're not in touch with the wrong sorts, or being groomed by baddies. Turns out, in Westminster at least, they are. Especially since it transpires that Tony Blair also texted Brooks last year, to wish her luck ahead of parliamentary questioning.

We send texts to our friends and our family, not to business associates, prospective employers or interested partisans. Texting implies a level of intimacy that seems entirely inappropriate given the balance of power, the increasing stink of corruption and the political import symbolised by the relationship between the current Prime Minister, one who formerly held that title and Ms Brooks.

There's something inherently collusive about texting, as well as something intrinsically anti-social and throwaway – no doubt that's why Cameron didn't think twice about dropping Brooks a line. But there in lies his terrible hubris. Texting is what adolescents do at the back of the bus; it's how lovers send their sweet nothings these days. It's a powerfully personal means of communication – one that won't necessarily be archived by your employers to check if you're bent or not; one that exists solely in your own domain and your own private life – quite literally, in your own hands.

Sending a text to wish someone well, to console them or let them know you are thinking of them is fine if they have broken their leg, split up with someone or failed their driving test. Sending a text to wish someone well when they are embroiled in a scandal is rather different. Especially should the text in question imply the degree of familiarity to which that person has been involved in shaping, or misshaping perhaps more fittingly, much of public policy. You can just imagine Brooks's phone, not so much vibrating as quaking with the volume of Machiavellian machinations it was party to.

Cameron's texts to Brooks – a woman whose first name already appears to be written in "textspeak" – is yet another facet of the cool, colloquial persona he has cultivated since even before he was elected. Dave, with his bike, his pasties, his Michael McIntyre DVDs and his texting; an accessible and universal latterday leader, man of the people and one of us. But this news suggests that the only vernacular he has really been speaking all this time is one of hand-in-glove hierarchy and hidden agendas. Clearly, Cameron's loyalties do not lie with us, the public.

Nor does he even sufficiently understand the medium to text properly. Brooks told the Leveson Inquiry yesterday that the PM used to sign off his twice a week messages with LOL until she told him it stood for "laugh out loud" rather than "lots of love". This is more embarrassing than William Hague's baseball cap. It paints a picture of Cameron, the great mum of state, putting on his reading glasses and holding his phone at arm's length to send his sordid missives. You get the impression that even Gordon Brown knew what ROFL meant. And he's probably doing just that right now.

(The Northerners among you will also have noticed that Dave should have told Brooks to keep her chin up, rather than her head. This simple, idiomatic mistake is perhaps proof of his alienating poshness, and besides her head is irrelevant; it will be chopped off and put on a spike at London Bridge soon enough. Won't it?)

The politics of texting are fraught enough as it is – Do you sign off with a kiss? How do you convey tone or warmth? – without it now becoming the medium of politicians, too. Generally a text is good for getting in touch when you don't really want to get involved, for ticking the communication box with none of the facial expressions, hand-wringing or balefulness of actual human interaction. No doubt, this is what Cameron had in mind.

What foolishness! This text, from its very existence to its content and the time of sending, says more than any phone call or email: more than the Chipping Norton dinners, or the racehorse, this text is proof that Cameron is personally friends – or allies, at least – with someone who has become the enemy of the people. And we know how that ended for Edward II, or Mary I, say.

But not only that, this text relationship has reduced Cameron's political stature significantly. Just as the tragic hero has gradually diminished in size and emotive power since the ancient days, so has the politician. They are ordinary men now, men with mobile phones. Imagine some of our greater leaders texting – "tho I have the body of a woman, I have the <3 and stomch of a king. LizR"; "men will say 'this woz thr finest hr. V. WC"; even "c u 7.30 @ Granita. Tx" – and understand how Cameron has undermined himself with this. He surely joins Squidgygate and Anthony Weiner in the insalubrious bracket of public figures embarrassed by private communications.

And Cameron has also delighted the left wing and conspiracy theorists alike with this curious slip in his usual Teflonic demeanour. The mind boggles at some of the things this Government has got away with – Osborne's coke-hooker past; Adam Werritty; the NHS reforms, to name but a few – but this text must surely be the final nail in its coffin. Cameron's opponents must be hugging themselves; in clicking "send", he has signed his own death warrant. C u l8r.