The father of a man who took his life after allegedly being bullied in the Conservative Party has demanded that the party chairman resign.
Ray Johnson, whose son Elliott Johnson, 21, was found dead on railway tracks in September, said responsibility for the tragedy rests on the shoulders of Lord Feldman as he was sole party chairman when concerns first arose.
The party has said an investigation into claims of bullying in the youth wing will be conducted "in its entirety" by the law firm Clifford Chance.
But pressure continues to mount on Lord Feldman - an old university friend of David Cameron who was co-chairman with Grant Shapps until the general election in May.
Mr Shapps announced at the weekend he was standing down as an international development minister following claims he failed to act on reports of bullying in Conservative Future.
But Mr Johnson said that so far Lord Feldman had failed to accept any responsibility for what happened and described Mr Shapps as "just the fall guy".
Speaking from his home in Wisbech, Cambridgeshire, he added: "Lord Feldman was the sole chairman at the time and quite simply any complaint of the nature my son was making would, in any other situation or organisation, have led to the person responsible being put immediately out to grass."
The allegations centre on the activities of the former activist Mark Clarke, who was expelled from the party earlier this month. Mr Clarke has strongly denied the allegations against him.
Mr Johnson says that his son's concerns were brought to the party's attention on August 12. He was found dead on railway tracks near Sandy station in Bedfordshire on September 15.
Mr Johnson said: "There was a month between my son making his complaint and him being found dead.
"If he had felt his complaint was being taken seriously and Mark Clarke had been suspended, maybe that would have altered his state of mind and he would still be here but the party failed to act.
"For me Lord Feldman is at the centre of this and has serious questions to answer.
"It seems that David Cameron regards him as indispensable but in my view he should resign and acknowledge the failings within the party."
He said he was pleased with the decision to bring in outside investigators but was keen to establish that the inquiry would be independent.
"This is definitely a step in the right direction - an internal investigation would never be seen as fair," Mr Johnson said.
"Until now the Conservative Party basically ignored what we were saying and carried on arrogantly in their own way.
"I have asked my lawyer to contact Clifford Chance to establish what the terms of reference will be.
"We need to establish that this will be investigated fully, not just in the way the party wants it to be."