Leveson Inquiry: Telegraph expenses scoop explained
The Daily Telegraph paid the middle man in the MPs' expenses story £150,000 for the disc containing the information, the Leveson Inquiry has heard.
Former editor Will Lewis said he was initially concerned the story was a hoax but soon realised he had a "responsibility" to publish it.
It was only when Jack Straw confirmed his expenses details he was confident to publish the story, he said.
He also denied the paper had dragged out its reporting for commercial gain.
"I was also aware of the fact that this story was laced with risk all around, as the best and most important public interest journalism tends to be," Mr Lewis told the inquiry into press ethics.
He said he consulted lawyers before entering negotiations to buy the data, but because the information had been copied on to a disc he was advised it did not constitute theft.
A Telegraph team in a secret room was given 10 days to make a preliminary examination of the material and soon found evidence of abuses of the parliamentary expenses system, he explained.
"They uncovered quite quickly things that no-one thought probable. Looking through such stuff, I became very aware that it was my responsibility to bring this to the public domain."
Mr Lewis said he had an ethical obligation to get the story into the open, and denied dragging it out for commercial gain.
"Some might say that it represents one of the most important bits of public service and public interest journalism in the post-war period that unveiled and revealed such wrong-doing in Parliament that the Speaker had to resign and many MPs followed after him," he said.
"It was a way to ensure that the readers of the Telegraph and the broader British public were able to find out about the profound wrong-doing in the House of Commons and how MPs had stolen from the taxpayer."
Mr Lewis now works for News International where he sits on News Corporation's management and standards committee, which is examining the phone-hacking scandal.
Earlier, Financial Times editor Lionel Barber told the inquiry his paper's code of conduct was "a model for self-regulation".
He said the code was stricter than the Press Complaints Commission's and there were severe penalties for breaching it.
Mr Barber said the PCC code was "pretty robust" but needed "to be enforced" and "credible".
Calling for a new regulation system, he said the closure of the News of the World had been a "wake-up call" which made executives realise changes were needed.
He said all journalists should sign up to a "new body of independent regulation which is robust, credible and worthy of joining".
Current Telegraph editor Tony Gallagher said the PCC was "clearly not fit for purpose" in its present form.
"I think one of the difficulties of the PCC is that it stands condemned for things it was never able to do," he said.
"I think the PCC has never had investigative powers, and I'd very much like it to have those, to be able to - when there's been a systemic breakdown in standards - go into newsrooms, interview staff, seek emails, demand an audit trail to see how decisions have been taken."