A Sun journalist who paid a police officer for tip-offs and other information about high-profile crimes was a liar and a cheat, her former deputy news editor told a court today.

Although the reporter known in court as Journalist A was "a nice girl", Ben O'Driscoll said he had problems with her professionally.

Dozens of her stories, he told Kingston Crown Court had "collapsed" because they appeared to be based on "little more than fantasy."

He said: "I took her with a pinch of salt."

Mr O'Driscoll, now deputy news editor of the Daily Mail, and five other past and present Sun journalists accused of conspiring to commit misconduct in public office.

The two month trial revolves around payments made by Sun journalists to police officers, a health care worker and other public officials.

In his third day in the witness box, Mr O'Driscoll was asked about payments made by Journalist A (who cannot be named) to a police officer in return for stories about the footballer Jack Wilshere and an accident involving the sister of singer Mika.

Asked about a Sun front page about Wilshere brawling, Mr O'Driscoll said: "My impression would have been that she [Journalist A] did not get the first tip on Wilshere and she was fishing for a cash payment."

There's no evidence here that a police officer was ever involved in a story about Jack Wilshere."

He said of a taxi receipt submitted by Journalist A for meeting her police contact after the story: "Maybe she was inflating her expenses. Taxi receipts are the easiest thing for a journalists to put through."

Journalist A emailed the newsdesk asking for £500 "cash for my cop" as a welcome back after he had a stint with the flying squad.

Mr O'Driscoll said: "I didn't believe that any of this was going to a police officer. She was a loose cannon and a maverick - a news editor's worst nightmare."

Cross-examining, Oliver Glasgow, for the Crown asked: "How is that she gets £500 in cash the same day, that goes all the way of the authorisation process for your level to the top?'

Mr O'Driscoll told the court: "I would love to know."

If the money really had gone to a police officer, Mr O'Driscoll agreed, it would have been a bribe. But he said: "I accept that she's asking for a bribe but I think this is getting a cash payment for herself."

He told the court: "Dozens of her stories would collapse and not make it into the paper and be based on little more than fantasy."

After a juror asked how a liar and a cheat could have kept her job at the Sun, Mr O'Driscoll said that often when she went out of the office "she could get stories."

Mr O'Driscoll told the court he was now "hugely embarrassed" about an email he sent to Journalist A in 2010 about Mika's sister being impaled on railings: "She's really pretty too. Great tale."

The six journalists deny all charges. The case continues.