Shear also told the inquiry that recent months have seen the 'greatest sensitivity, fewest stories and least intrusion' in the press
Shear, who has represented a number of public figures in legal actions against the press and also believes he himself was a victim of phone hacking, told the committee that from 2004/2005 "clients began to believe that coincidences were being replaced by more likely interception of some form or another".
"Clients were becoming irritated, or frustrated, or suspicious that private information was finding its way into the popular media. Stray facts they knew were only privy to one or two people were being published. This caused them to ask questions of family, friends and even of me.
"I recall it quite clearly. It became so continuous that suspicion became more focused on whether or not this was being obtained by surveillance. Those I acted for became more used to changing their mobile telephone numbers two or three times a year, a common way for people to give themselves some confidence, although no evidence, that could prevent easy access to information about them."
During his appearance before the inquiry Shear also criticised the Press Complaints Commission (PCC), calling for it to work on encouraging greater ethics training for journalists.
"Without having teeth to regulate members of media [the PCC] are an ineffective body. There is also an issue of training and where one has a systemic loss or dilution of ethics to the extent we've seen at the News of the World, although I don't believe it was isolated to that paper, one has to question the extent to which journalists are trained ... to act ethically and that element should also be introduced into any body that replaces the PCC or any enhancement to the PCC's powers."
He also told Lord Leveson in direct questioning from the judge leading the inquiry, that in recent months the industry has seen the "greatest sensitivity and fewest stories and least intrusion", which he linked to the press being placed under the "microscope of this inquiry and the prospect of phone hacking claims".
"When one goes backwards in time, from 2003/4 to 2005. I think there was an atmosphere of not just complacency but that they were almost untouchable, so activities became incredibly intrusive and a fever pitch of trying to produce more and more detailed stories with far lower recognition for either consequences or further private rights. This accelerated and increased from 2003 to 2008/9 and has now receded. Whether it's temporary because of the focus of this inquiry only time will tell."
Earlier in his evidence Shear also told the inquiry that in recent times newspapers were also less likely to put stories to subjects before publication.
"I did have good relationships [with newspapers]. During the early part of 2008/9, even now occasionally, papers would alert us to a story and that was certainly more prevalent the further one goes back than currently."
He added that he would ask the legal department to inform him of any material being considered for publication which may involve his clients.
"Certainly up until the last few years legal departments would put that material to us. Over time the amount of damages awarded in relation to defamation has reduced so it's been on a sliding scale downwards and the maximum amounts provided by way of damages in breach of privacy have been relatively modest. If a news organisation can calculate financial consequences post-publication they can calculate the benefits of publishing stories without approaching the target first.
"So what I have seen is a reluctance by the media to put stories pre-publication and stand back and await the fallout after publication. There are two effects, firstly some people view it as once stable door is open what's the point in litigating after the event, this only reminds the reader and those who perhaps didn't read of private information in first place, and secondly, so far as defamatory material is concerned, there's an easier outcome for defendants in any action post-publication and that's to make an offer to satisfy the claim."
He added that he has "run more pre-publication anonymity injunctions than possibly any other lawyer in the area".
"At one point I was in confrontation with larger newspaper groups almost every weekend", he said, but added that "over last few years that's receded dramatically."
Former FIA chief Max Mosley recently lost an appeal to the Grand Chamber, as part of his legal challenge to introduce a "prior notification" law to make newspapers warn subjects of stories before publication.