British police are to spend a year reading through the private papers of the late-former prime minister Edward Heath as part of an inquiry into sex abuse allegations.

Wiltshire Constabulary is recruiting civilian investigators – usually retired officers – to examine the archive of the late Conservative PM who died in 2005 after several claims of sexual abuse surfaced.

Detectives will search through 4,500 boxes of uncatalogued material, which includes diaries and personal letters, all of which are held in the Sir Edward Heath archive at the Bodleian Library in Oxford.

The investigation comes in response to at least seven allegations of abuse brought against Heath, including one claim the former PM abused a boy on his yacht before throwing him overboard.

Ted Heath’s name passed to “VIP paedophile network” police inquiry http://t.co/ruyQYIkRWzpic.twitter.com/3xe6osG1kR — RT UK (@RTUKnews) August 5, 2015

The Times reports that police will question former political aides, housekeepers, cooks, household staff, musicians and even guests who visited him for lunch at his home in Salisbury, Wiltshire.

The inquiry has been prompted by a retired officer’s claim last year that abuse allegations against Heath were covered up in the 1990s.

A retired Wiltshire police officer, who reached a senior rank in the force, revealed that a case involving a brothel owner had been dropped when she said she would expose Heath.

A colleague of the whistleblower, another retired officer, said he is sure the allegations will prove to be true.

‘Sir Edward Heath abused my 14yo friend at paedo parties’ Jimmy Savile’s nephew alleges http://t.co/R2kVevbyJ7pic.twitter.com/UIcQXfHTeu — RT UK (@RTUKnews) August 7, 2015

He told the Daily Mail last August: “I have no doubt that the allegation that a prosecution was stopped in suspicious circumstances, because of a potential link to Sir Edward, is true.”

Heath’s principal private secretary Lord Armstrong of Ilminster believes Heath was asexual and that police are “barking up the wrong tree.”

“All the allegations of which I am aware are totally tenuous and not credible … if there’s nothing more than that to go on I can’t believe that it is worth spending a lot of resources in this way to pursue somebody who’s dead.”

“I very much regret the slur on Edward Heath and I always regret the consumption of public resources on this scale for what seems to be an unnecessary inquiry.”

VIP paedophile allegations in Operation Midland lack evidence - reports https://t.co/U2TJvgKBX3pic.twitter.com/Td1VxQJx3T — RT UK (@RTUKnews) February 15, 2016

Heath was also implicated in Operation Midland, an investigation into a suspected Westminster VIP pedophile ring which has failed to turn up any evidence despite entering its fifteenth month.

The Independent Police Complaints Commission (IPCC) is separately investigating a retired officer’s allegations that a case against a brother owner was dropped in 1992 when she threatened to expose Heath.

Allegations to be investigated by Wiltshire police may include claims Heath abused children on board his private yacht, Morning Cloud.This allegation has reportedly been undermined by his former navigator, who said the vessel needed a crew of three and had no private space.

Wiltshire police told the Times it would not comment on an investigation in progress.