Thurlbeck claims Watson broke 'the code of confidentiality that exists between journalist and politician'Credit: Yui Mok/PA
Thurlbeck – who is quoted in Dial M for Murdoch describing an alleged edict from News International to carry out surveillance on Watson and dig out private information about other members of the media select committee – said Watson "chose to break the code of confidentiality".
He wrote in a blog post: "Much has been made of Tom Watson repeating our private conversation in his new book. I can't say I'm anything more than surprised and disappointed. No real depth of feeling about the matter, although others may have a different reaction.
"The information I relayed to Tom Watson was done so in the run up to submitting my written report to the Select Committee for Culture, Media and Sport last year.
"One would normally assume as I was using his offices to do this, I would automatically be accorded a degree of confidentiality. We agreed verbally that this was the case in October, when he came to my home, and we agreed it before we met in his Commons office some weeks later."
Thurlbeck described an email exchange between the two of them, marked "private and confidential". He said in the blog post that some of the questions being asked by Watson meant he "was beginning to suspect Mr Watson was using his parliamentary role as a subterfuge for gleaning information for his book".
He added: "I'm not remotely angry with Tom Watson, I simply want to set the record straight. If anything, I'm just irritated that he can't seem to hold a confidence when he is meant to be probing serious wrongdoing.
"Tom Watson had two agendas that day – for parliament and for his book. And he chose to break the code of confidentiality that exists between journalist and politician. His book and the committee's report next month will be a testament as to whether this was justified."
Thurlbeck is quoted in the book saying: "All I know is that, when the DCMS [Department for Culture, Media and Sport Select Committee] was formed or rather when it got on to all the hacking stuff, there was an edict came down from the editor and it was find out every single thing you can about every single member: who was gay, who had affairs, anything we can use.
"Each reporter was given two members and there were six reporters that went on for around 10 days. I don't know who looked at you. It fell by the wayside; I think even Ian Edmondson [the news editor] realised there was something quite horrible about doing this."
Thurlbeck said he had been told that the decision to carry out surveillance on MPs was made by "News International, not the News of the World", adding: "It wasn't journalism. It was corporate espionage."
Watson replied on Twitter this weekend: "For those interested, I will respond to Neville thurlbeck's recent blog post. It requires time to do it properly."