The former chairman of the Conservative Party, Grant Shapps MP, has stepped down from his ministerial post today (28 November). Shapps has been accused of failing to prevent bullying within the Conservative Party's youth wing which has been linked to the suicide of 21-year-old activist Elliott Johnson.

Shapps' position was looking increasingly vulnerable after British Prime Minister David Cameron had refused to lend his support and Elliott Johnson's father, Ray Johnson, said Shapps should resign.

Shapps and Lord Feldman, the party's current chairman, have both been accused of failing to act on complaints against the Conservative Future organiser Mark Clarke. British Transport Police launched an investigation into claims of bullying after the discovery of Johnson's body by train tracks in Bedfordshire in September.

In his resignation letter, the former minister for international development told David Cameron that the "buck should stop with me" concerning issues whilst he was party co-chairman. He added that he could not find any record of any written allegations of bullying, sexual abuse or blackmail that were made to his office.

"I cannot help but feel that the steady stream of those who raised smaller, more nuanced, objections should have perhaps set alarm bells ringing sooner," Shapps wrote in his letter. "In the end, I signed that letter appointing Mark Clarke 'director of Road Trip' and I firmly believe that whatever the rights and wrongs of a serious case like this, responsibility should rest somewhere.

"Over the past few weeks – as individual allegations have come to light – I have come to the conclusion that the buck should stop with me."

The British Prime Minister was asked about the bullying scandal at a Commonwealth summit in Malta. The Guardian reported he replied: "I think it is important that on the tragic case that took place that the coroner's inquiry is allowed to proceed properly.

"I feel deeply for his parents, It is an appalling loss to suffer and that is why it is so important there is a proper coroner's inquiry. In terms of what the Conservative party should do, there should be and there is a proper inquiry that asks all the questions as people come forward.

"It is a tragic loss of a talented young life and it is not something any parent should go through and I feel for them deeply."

Bullying accusations

The Conservative Party has been engulfed by allegations of bullying, sexual harassment and blackmail since Johnson died. It is claimed that Mark Clarke – known as the 'Tatler Tory' after he posed for the magazine – was sexually aggressive towards female activists, and blackmailed and bullied other members of the party.

Earlier this month, the Guardian reported that Clarke had been suspended from the Conservative Party, before being banned from it for life. Johnson's father told the newspaper that Clarke's expulsion was a "whitewash".

It has also emerged that Clarke had told MPs that he had been offered a safe seat in the 2020 general for his campaign work, implicating Shapps when he was still co-party chairman.

A number of sources have said they sent written complaints to Shapps detailing the accusations of bullying and harassment against Clarke. Elliot's father has claimed that his son would still be alive if Shapps had taken the accusations seriously and suspended Clarke at the time.

"They need to stand down. You wonder about the people running the country whether they're fit to govern," Ray Johnson told the Guardian. "If they had behaved responsibly, like any other organisation, none of these events would have happened; my son would still be alive and many activists wouldn't have been intimidated and harassed."

Investigation call

Jonathan Ashworth MP, Labour's shadow minister without portfolio, has said that the accusations of bullying, and Shapps alleged inaction, should be the subject of an independent investigation: "Every day seems to bring new questions with suggestions that warnings of bullying were ignored by senior Conservatives. Grant Shapps' resignation doesn't end this – we need to know just how widely this goes.

"The time has come for the Conservatives to put an end to the drip, drip of revelations. We need a fully independent inquiry – not one led by a Tory insider – to look at culture and practices in David Cameron's Tory Party and a commitment to publish it. As the prime minister used to say, sunlight is the best disinfectant."

Shapps was sacked from David Cameron's cabinet in May amid claims that he edited Wikipedia pages of other politicians – which Shapps denied – and after he admitted to posing as a businessman, Michael Green, in 2006, after being elected as MP for Welwyn Hatfield in 2005.

A spokesman from the Conservative Party has said the party will make a statement later today.

UPDATE 16:43 – Statements by Grant Shapps and Prime Minister David Cameron added.