LONDON (AP) — Secret documents found in a taxi. Private campaign plans publicized in high-octane tabloids. Embarrassing revelations about plans to steal a rival's approach. Instructions to characterize Prime Minister Gordon Brown as "weird."

The saga of the lost and found dossier relating to Liberal Democrat leader Nick Clegg's debate preparations has added a new twist to Campaign 2010, already one of closest and most unpredictable in recent British history.

Sloppy staffers seem to be at fault. Someone left handwritten notes advising Clegg on how to handle the upcoming debate with Brown and Conservative Party chief David Cameron were left behind in a cab. Inevitably, they were leaked to The Sun newspaper, which published them Wednesday.

The notes show that Clegg — who has made a meteoric rise in the polls since winning the first debate last week — is being told to copy Cameron's approach during the debate Thursday night, which focuses on foreign policy.

"DC (David Cameron) talks a lot in the language of values," the dossier states. "We need to do this."

If imitation is the sincerest form of flattery, Cameron should be glowing with pleasure. But chances are he is not pleased with events — the surprising Clegg surge has tarnished Cameron's once-shiny aura of invincibility.

Previously a distant third, Clegg has drawn close in a number of respected polls, capitalizing on the public's apparent distrust of the two major parties, who have traded power for decades.

Clegg Wednesday laughed off the publication of the debate notes, which his campaign conceded were authentic.

"I'm glad to see my top team preparing for government by developing a habit of leaving secret dossiers in the back of cabs," he said.

It was a reference to the loss in recent years of a handful of secret government documents, including some computerized intelligence files, that were accidentally left in public places, including trains.

The upstart candidate also denied that he planned to copy Cameron, or anyone else, when the high-definition TV cameras focus on the candidates debate Thursday night.

"Look, I've always been advised just to be myself in the TV debates and that's exactly what I was and what I will continue to be," said Clegg.

The notes, contained in an oddly named booklet called "I'm not here right now," were written by former ad man John Sharkey, a top Clegg adviser.

In the dossier, Clegg is advised to stand apart from Brown and Cameron during the debate and to accuse his opponents of not living "in the real world" and not understanding the problems real people face.

He is also warned, in capital letters for emphasis, not to fall into the trap of seeming to advocate giving up Britain's arsenal when discussing defense policy.

"AVOID UNILATERAL DISARMAMENT IMPLICATON" it says, in what seems to be a reference to the Liberal Democrat's pledge to stop replacing the expensive Trident nuclear submarines.

The notes imply that party leaders are concerned about appearing soft on defense.

In the dossier, Clegg's debate performance is criticized as he is urged to speak more slowly and with more passion and conviction. The candidate is also advised to appear more relaxed and to give short, simple answers.