Senior Mirror Group editor 'regularly paid private investigators for mobile phone numbers and private pin access codes' Invoices for the service that have been shown to The Independent, name the news executive but today the former Mirror employee - who cannot be identified for legal reasons - said he could not discuss the significance of evidence held by the Metropolitan Police. He said: "All of this should be referred to Trinity Mirror." Shares in Trinity Mirror, publisher of the Daily Mirror, Sunday Mirror and People, today plummeted by £20m after it was revealed that four high-profile individuals, including the former England football manager, Sven-Goran Eriksson, had begun legal action claiming their phones were hacked by Mirror newspapers. The claims filed at the High Court yesterday, which allege "breach of confidence and misuse of private information" relating to illegal mobile phone voicemail interceptions, is the first significant expansion of phone hacking in the UK beyond Rupert Murdoch's News International titles. The three other claimants are the Coronation street actress, Shobna Gulati, the former nanny of star footballer David Bekham, Abbie Gibson, and the former captain of Blackburn Rovers, Garry Flitcroft. The regimes of three Trinity Mirror editors are implicated in the claims, including Piers Morgan who edited the Daily Mirror between 1995 and 2004 and was in charge of the title when it revealed the affair between Mr Eriksson and broadcaster Ulrika Jonsson in a story that is at the centre of the football manager's complaint. Mr Morgan, now a star interviewer on the US news channel CNN, has repeatedly said he has no knowledge of phone hacking happening during his editorship. Tonight the lawyer representing the new claimants, Mark Lewis, said that since the news broke of the allegations against the Mirror titles, others had contacted him. "They have raised issues that I will now have to look into," he said. Trinity Mirror has consistently tried to distance itself from illegal practices that were adopted inside titles run by Rupert Murdoch's UK print operation. Today the company repeated assurances given to the Leveson Inquiry earlier this year by its former chief executive, Sly Bailey, stating that "all" its journalists worked "within the criminal law and the Press Complaints Commission Code of Conduct." However a former Trinity Mirror journalist who today spoke to The Independent on condition of anonymity, repeated the allegations given to the Leveson Inquiry last year by the Mirror's former business writer, James Hipwell, who claimed he had personally been shown "how to hack" by the paper's showbusiness team. The former journalist, building on Mr Hipwell's account, said staff were bullied into hacking, that it was common knowledge and that voicemail interceptions took place from the 1990s to well into the 2000s. The Independent was told "It started off as a cult activity by showbiz reporters. It was a plentiful source of cheap diary stories, but then it became proven that it broke big stories, and the news people started to use it and the showbiz people started to get promoted into news - and they would insist it was used. It became standard practice. Backing up Mr Hipwell's Leveson testimony, the source said they had first-hand knowledge of its use, knew people who "were at it" and that it was done openly in Trinity Mirror titles. They added "It was done with authority. Political decisions [within the offices] were made that this was what people had to do - even if it was against their will. Alleging that senior Trinity Mirror management knew of the illegal practice, and were involved in keeping it a secret, could, if proven, be financially damaging for the struggling publishing group. Being part of the Murdoch-owned News Corp has allowed News International to both mount a robust legal fight-back against phone hacking, while at the same time bowing to the inevitable high-tariff damages that have arisen from scores of settled civil claims. That process is still on-going with NI's final hacking bill now expected to soar past the £200 million mark. Trinity Mirror are without such financial muscle. Its share price has fallen 90 percent over the last five years, and at the close of last year was servicing debt of around £220 million. Company insiders are now saying that Ms Bailey's decision taken last year not to order an investigation along the lines of NI's "management standards committee" (MSC) review, could now be reviewed. She explained her decision to Lord Justice Leveson saying that as there was no evidence Mirror Group journalists had hacked phone, there was no need to conduct an investigation. In place of a detailed investigation, Paul Vickers, the company's legal director, who is a former barrister, varied out a review of editorial controls and procedures. A company spokesman said Mr Vickers review "had no historical element to it, and simply examined existing practices." The spokesman said they would be making no comment on any evidence held by Scotland Yard, and as it had yet to receive any claims from Mark Lewis could add nothing more.