Surrey Police blamed for not following up suspicions over Milly Dowler's voicemail

Force failed to investigate NOTW in 2002 despite suspecting it of hacking into teenager's mobile

Surrey Police are under renewed pressure to explain their nine-year silence over what exactly they knew about the News of the World's criminal activities during the initial stages of the Milly Dowler murder investigation.

The Leveson Inquiry confirmed yesterday that the Surrey force logged a "suspicion" in April 2002 that the Sunday tabloid was responsible for the deletion of voicemails from the mobile phone of the then-missing schoolgirl.

The public outcry last July, following an article in The Guardian which claimed that NOTW reporters had deleted voicemails on the schoolgirl's phone, was a key factor in forcing the Government to set up the press practices and ethics inquiry.

Within weeks of the Dowler revelations, Rupert Murdoch ordered the closure of the top-selling tabloid. Mr Murdoch later approved a £3m damages payout to Milly's parents.

Evidence from Detective Constable John Lyndon recorded in April 2002 suggests that Surrey police had already been focusing on Milly's voicemails from an early stage of their investigations, had talked to her mobile provider, and suspected that the NOTW or someone else had listened to voicemails, which could have been deleted.

The new focus on Surrey's failures is part of an update on Scotland Yard's phone hacking investigation ordered by Lord Justice Leveson last December. But the report by Detective Chief Inspector John Macdonald said the full truth about the hacking of the teenager's phone may never be known.

The Met officer said it was "not possible to state with any certainty whether Milly's voicemails were or were not deleted." The five-month re-examination looked at new technical information provided by her phone provider. Although Operation Weeting remains engaged in "further enquiries", the report admits further clarity on what happened to the phone messages is unlikely. The report says, in effect, that what Surrey Police could have done in 2002 is no longer possible in 2012. Call data that was available when Milly went missing is no longer there, and "the fact that 10 years have elapsed since that time [means] we will not be able to obtain a definitive explanation".

Last night the Labour MP Chris Bryant said: "It is still completely inexplicable why Surrey police did nothing about this for years. It is as if they were colluding with the News of the World. They knew what had happened and failed the Dowler family and the public by failing to take action."

Surrey Police said yesterday it was in the final stages of its "Operation Baronet", into the way Milly's voicemail messages were accessed in 2002. Its statement said: "The Force accepts that we failed to investigate this at the time and former Chief Constable Mark Rowley has discussed this issue with the Dowler family at a meeting in July last year. We deeply regret any distress this has caused them." The report is expected at the end of May.

Public revulsion over the NOTW's illegal actions centred on Milly's parents trying to call their daughter's phone when she went missing in 2002. She had a generic message that indicated when her mailbox was full. If a message was deleted it would revert to a personal message.

Sally Dowler told the Leveson Inquiry last year that she called, heard the personal message, and in a "false hope" moment believed her daughter was still alive. The new report said this was likely to have been caused by an automatic purge of messages.

Last July, The Guardian described the deletions by the NOTW as "fact". Yesterday their lawyer, Gill Phillips, acknowledged this was not the case.

Look, Hugh's talking... Grant pays inquiry a surprise visit

Hugh Grant surprised even Lord Justice Leveson yesterday when he turned up unannounced and sat in the front row of the public seats of the inquiry into press standards.

Mr Grant – who claimed in evidence to the inquiry last year that he believed his phone was hacked by the Mail on Sunday, something the newspaper denies – watched testimony from behind a large pair of glasses with a quizzical look on his face.

The actor told reporters it was merely a coincidence he was near the High Court and that he had decided to drop in because he had an hour to spare.

Rob Hastings