Jeffrey Archer's requests for alibis to cover up his extramarital affairs were "not out of the ordinary", the Old Bailey was told yesterday.
His former friend Ted Francis had detailed many infidelities, including one in Nigeria and another that had "landed him in trouble" with Lady Archer.
However Mr Francis believed the best-selling author had asked him to provide a false alibi for an infidelity and not for Lord Archer of Weston-super-Mare's high-profile libel trial against the Daily Star in 1987, the court was told.
Neville Thurlbeck, a News of the World reporter, told the court it was only after the trial that Mr Francis realised he had been asked to provide a false alibi to help with the court case and not to get Lord Archer off the hook with Lady Archer.
But the alibi, for the night of Tuesday 9 September 1986, was never used because the Daily Star instead alleged that Lord Archer, then the deputy chairman of the Conservative Party, had sex with a prostitute on the night before, 8 September.
Mr Thurlbeck told the court yesterday that during his own conversations with Mr Francis, he had "cited many infidelities" relating to Lord Archer.
He said it was only "subsequent" to the trial that Mr Francis realised the false alibi had not been intended for a marital indiscretion.
The publicist Max Clifford told the court last week that Mr Francis approached him about a story concerning the alibi because he did not want Lord Archer to be Mayor of London. Mr Thurlbeck said Mr Francis had thought long and hard before agreeing to have his telephone conversations with Lord Archer taped by the News of the World.
Stuart Kuttner, managing editor of the News of the World, said he and the editor, Phil Hall, went to see Lord Archer two days before publishing their story. Mr Kuttner said: "He responded initially by effectively denying the information we brought to him but fairly rapidly came round to what seemed to be an acceptance of what we were saying. He pointed out that he did not believe anything illegal or unlawful had occurred. He stressed that he hoped the story would be on the inside page rather than the front page."
Mr Hall, who is now editor of Hello! magazine, said Mr Francis was paid £19,000 for his story, which included £5,000 to charity, and the price of a second-hand car.
Lord Archer and Mr Francis face dishonesty charges after the News of the World revealed in November 1999 that Mr Francis had been asked before the trial to provide a false alibi for 9 September 1986. Lord Archer stood down as Tory candidate for Mayor of London after the story was published.
Lord Archer, 61, won £500,000 damages in 1987, which he said he would give to charity. The novelist denies four counts of perverting the course of justice, two counts of perjury and one of using a diary as a false instrument. Mr Francis denies one charge of perverting the course of justice. The trial continues today.