Imitation - the old saying goes - is the sincerest form of flattery. And there is no doubt that Team Cameron, however much they deny it, are imitating Tony Blair's electoral strategy.
So, a charismatic young opposition leader, long on confidence if short on experience and policies, pledges to change his party and prove he's up to changing Britain.
Thus Mr Cameron today tried to re-write the rules of Question Time by pledging to back the prime minister against the opposition of many on his own side. Thus he travels to a deprived area of East London to talk to a multi-racial audience about social justice.
Thus he will take on his own party over the selection of more women candidates. He does it all with a following wind from those parts of the media who sense - and even hope - that the Blair era is coming to an end.
But hold on a minute. It was Mr Blair with Mr Brown who wrote the handbook for this strategy and they think they know how to defeat it. This time they will take on the ball and not the man, believing that it's policy which will be Mr Cameron's undoing - whether backing selection in schools, tax cuts or confrontation in Europe. It'll be a fascinating contest.
If you don't believe me you may wish to consider a quote from a younger George Osborne interviewed for a documentary about the Hague years I made some time ago for BBC Two: "We want a new leader, a new generation to do in effect for our party what Tony Blair did for the Labour Party."
In this part of the capital, at least, there's no sign yet of the demise of Punch or Judy.
So, DC's first appearance at Prime Minister's Questions. What an extraordinary display of confidence the new boy gave - more so than Tony Blair when he first did it, as the archive report below shows. But the question some people will be asking themselves is was there too much confidence?
Clearly, telling Mr Blair that he had been the future once will go down as being the line of the day - and it's one David Cameron might find being repeated again and again in the coming years. Is this quite the thing to say on your first day in the job, some people will be asking, or does it show a touch of arrogance?
DC did try to live up to his promise to scrap the Punch and Judy show by pledging to back the PM on education. Tony Blair saw this promise of a new consensus coming - and that's why he too dropped the aggression - even to the point of refraining from jabbing his finger at the opposition benches (although he forgot on one occasion).
He even took off his glasses so that he could use them to gesture with instead of pointing. This is a trick Harold Wilson used, - he was given a pipe by early spin doctors to stop him gesturing aggressively (right). Tony Blair with a pipe... Now there's a thought.
Amid all the Tory euphoria, and the comparison with Tony Blair, DC will remember that he's in a very different situation from Mr Blair, who already had a hefty lead in the polls when he took over. Mr Cameron knows he is in far from that position.
My enterprising colleagues in the newsroom have dug out the report of Tony Blair's first appearance as leader of the opposition at Prime Minister's Questions, in which he told the BBC that he wanted to get away from "soundbite politics". (You can see that archive report here.) The parallels don't end there - the first question he asked was about the chancellor of the exchequer - then, as now, seen as being at odds with the prime minister. Deliciously, Tony Blair, who always accuses the Tories of being obsessed with Europe, also mentioned precisely that subject.
Talking of courtesy, it is one hugely underrated quality that both main party leaders share. That and a sense of humour.
Over the years Tony Blair has been labelled a traitor, a Tory (even worse from his point of view), and a war criminal by his own supporters and commentators. Yet I cannot recall an occasion on which he's shown more than slight exasperation. He doesn't snap back and, more often than not, smiles wearily in a way which has the viewer on his side.
David Cameron shows the same quality - laughing off Jeremy Paxman's aggressive questions and, yesterday, one from me. I - somewhat churlishly - pointed out that I'd been to five euphoric unveilings of a new Tory leader and yet every leader to date - Major, Hague, IDS and Howard - could be described by one word - "loser".
What, I enquired, made him different? I'm told that his staff panicked. This was one question they hadn't prepared for. Cameron didn't. He smiled and said: "Nick, this is my first." Laughter all round. Robinson left slightly red-faced. I wonder if that's what they teach at the best public schools?
So farewell then Punch & Judy. It's a turn off. It's outdated. It's aggression for its own sake. So very last century.
Who says so? Why none other than the new leader of the Tory party just hours before his first clash (sorry, there I go again) with Tony Blair at Question Time. What's more, the PM himself said as much when challenged to change the tone by a new MP last week on the occasion of Michael Howard's farewell.
So, in a little over an hour's time, no doubt we will hear Messrs Cameron and Blair fall over each other to be the first to praise their opponent's policies and to exchange in detailed policy analysis. Mmmm. I wonder.
The Guardian today helpfully re-prints DC's musings (he did a kind of blog for the paper) on the first time he asked a question at Question Time.
In it he defends the parliamentary bear pit as a great democratic test of whether leaders have got it. It's worth remembering that we have heard this sort of thing before from previous Tory leaders and indeed from Mr Blair himself from time to time. They both read the same opinion polls but they also both know that PMQs - like the school playground - is the place you have to demonstrate your strength if your gang are to stay onside.
I suspect what DC will try to do is to avoid the witty Hague-ite soundbites - in part because he's not very good at them and in part because they give Labour MPs an excuse to rally to their leader - and focus instead on questions designed to tell the country more about him and his priorities than about the failings of Tony Blair.
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