The Conservatives are hampering police by withholding the contents of an internal bullying inquiry, the father of a young party activist who took his own life has said.

An inquiry was launched after the death of Elliott Johnson, who campaigned for the Tories in the 2015 general election.

The party said it has released as much information without jeopardising the anonymity of witnesses, but British Transport Police, which is investigating the 21-year-old's death on a railway in Bedfordshire, said it had requested the report but had not yet received it.

And Ray Johnson said the party is "not prepared to divulge what really happened" during the period leading up to his son's death.

Speaking to the Press Association, the 59-year-old said: "They (the Conservatives) feel they are the guardians of the truth in this matter and they are not prepared to divulge what really happened to my son, to us, or even to the police.

The Herald:

"They are hiding behind the very scant guarantee of anonymity to the witnesses."

A law firm commissioned by the party to investigate allegations of bullying and the handling of several complaints about a key activist in the youth campaign returned its report in August.

The Conservative Party said it had released "as much of the report as was possible", without publishing information that would lead to the identification of witnesses who gave evidence on condition of anonymity.

But Mr Johnson said he is not calling for names to be made public and that it is the police who are "best situated" to protect the anonymity of the witnesses.

He said in withholding the findings, the Tories are "only protecting themselves".

"The police want to continue their investigation into my son's death and they are being hampered by the Conservative party and the question is why?" Mr Johnson said.

"I believe the Conservatives have things to hide, things which affect senior members of the Conservatives office."

A British Transport Police spokeswoman confirmed to the Press Association that they have "made requests for the report but have not yet received it".

Mr Johnson said a letter sent by Tory party chairman Sir Patrick McLoughlin last year contained assurances that Sir Patrick would "assist the police" in their investigation.

But he later discovered the police "had made several requests" for the report and that these "had not been complied with".

"So I wrote back to him and said 'hang on, you told me you would support the police and I have discovered they have asked at least twice and you've failed to do that'," Mr Johnson said.

"And I just got a very curt reply saying he had nothing further to add. That was clear I had rumbled him and his guarantee to support the police was worthless."

He said he wants the "vital report" sent to the police, something he said he will continue to pursue until it happens and he has "full knowledge" of why his son died.

Mr Johnson was hit by a train and killed at Sandy station in Bedfordshire on September 15 2015, just weeks after making allegations about his treatment within the Tory party.

Prior to the general election, he worked on a campaign to take young activists around the country in support of Conservative candidates.

The Clifford Chance investigation found party activist Mark Clarke, the so-called "Tatler Tory", was appointed to lead the RoadTrip campaign despite warnings of his past record of "aggressive" conduct.

The probe found that complaints were made about the conduct of Mr Clarke on seven occasions before the party finally mounted an investigation into his behaviour.

The report said the party's then co-chairmen Lord Feldman and Grant Shapps had not been made aware of the allegations until August 2015 when an internal party inquiry was launched.

It noted Mr Shapps had seen an internal party report that referred to Mr Clarke's past "aggressive and bullying conduct" when he appointed him to head a Conservative youth campaign drive.

Mr Clarke, who has always denied the allegations against him, refused to be interviewed by Clifford Chance, although his solicitors told the inquiry he was continuing to cooperate with the police and coroner investigating Mr Johnson's death.