Former Sun editor Kelvin Mackenzie told phone hacking campaigner and MP Tom Watson to "shut up" and "go back to sleep" in an extraordinary exchange on Saturday morning.
During a debate on BBC Radio 4's Today programme Mackenzie claimed Rupert Murdoch's new paper The Sun on Sunday would be a great success and "Rupert would be mad not to start the paper."
Sparks flew, however, when the two discussed allegations that staff at The Sun had paid police for information.
Kelvin Mackenzie: Tell me Mr Watson - how do you feel about somebody who, through their taxpayer funded expenses might have used their money to convert a taxpayer funded flat from a leasehold to a freehold that was exposed thanks to the whistleblowing of somebody - wholly illeagally, presumably, being paid £150,000 by The Daily Telegraph to nail people like you. How do you feel about that, Mr Watson? Answer that question.
Tom Watson: That information would have been in the public domain, Kelvin, and you know that.
Kelvin Mackenzie: How would they have worked it out without The Daily Telegraph paying the money? Whistleblowing is aimed at people like you, Mr Watson, don't ever forget it.
Tom Watson: Kelvin, don't worry. Let me also defend tabloid journalism as well. Some of those good journalists on The Sun have been undermined by this process and in many senses they're paying the price for the legacy that Kelvin Mackenzie left. You've...
Kelvin Mackenzie: Oh shut up, shut up Watson. Go back to sleep.
The exchange led to Mackenzie trending on Twitter, with many users of the social networking site unimpressed.
Watson himself later tweeted he could not stop chuckling about the exchange.
During the interview, the Labour MP also expressed concerns about The Sun lifting suspension on journalists who had been arrested.
"We know from Parliament that executives of News International were found guilty of collective amnesia. I think the police need to give reassurance to the public that in allowing suspects who are innocent until proven guilty back into what is effectively the scene of the crime, that the evidence is secure and safe," he said.
"I am writing to [Met Police chief] Bernard Hogan-Howe to ask how he is going to secure the evidence in the Sun newspaper if these people return to work. Some of those good journalists have been undermined by this, and they are paying the price by the legacy Kelvin Mackenzie left. This man defends payments to police."
Listen to the two below