He told a jury that a story in the Independent questioned the legality of including pounds 7.23m from two overseas film rights sales in record 1987 profits.
The article said the money helped to turn the group into one of Britain's largest leisure conglomerates.
Mr Walker, a former boxer, who denies masterminding a multi-million-pound fraud involving bogus profits, said he was 'most concerned' at what was being suggested and moved quickly to investigate what he regarded as untrue claims.
He told Southwark Crown Court that shortly after the allegations were published in August 1988, he suggested that a wholly independent third party carry out an in-depth probe into the claims and report on the validity of the sales.
But the board decided instead to put the matter into the hands of the company's lawyers and auditors.
They were instructed to investigate the genuineness of the contracts questioned in the Independent; whether there were any profits from the deals; and if those sums were properly included in the accounts.
Mr Walker told the court: 'As far as I was concerned, the contracts were totally right.'
His company was being accused of malpractice, he said, and it was necessary that the investigation be very thorough and those carrying it out should have access to whatever documents they required.
In the event, the investigation cleared Brent Walker of any wrongdoing and a company issued a press release to that effect.
Mr Walker said that despite the inquiry's satisfactory outcome, he and his co-defendant, Wilfred Aquilina, decided to look at the whole picture of Brent Walker's film contracts.
Mr Walker and Mr Aquilina, the group's former finance director, plead not guilty to two joint charges of false accounting, one of theft and one of conspiracy to falsify accounts.
Mr Walker is also accused of three theft charges and his former colleague of one charge of false accounting.
Mr Walker is alleged to have stolen pounds 17m from the company, which the prosecution claims was laundered through overseas institutions before being fed back into the group.
The trial was adjourned until today.Reuse content