Former Tory chairmen Grant Shapps and Andrew Feldman were not aware of bullying within Conservative party headquarters, an official investigation has concluded.

The inquiry was launched last year following the death of Elliott Johnson, the Tory activist who claimed in a suicide note he had been bullied by fellow activist and former candidate Mark Clarke.

Law firm Clifford Chance was tasked with conducting the investigation into bullying within Conservative party headquarters.

It has now identified 13 alleged victims of Clarke, including six allegations of sexual assault. Clarke did not take part in the inquiry but has previously denied all allegations of wrongdoing.

Both Shapps and Feldman had faced criticism last year for failing to deal with complaints about bullying. Shapps resigned from the cabinet last November over the claims, saying “the buck should stop with me”.

The report from Clifford Chance revealed that Tory spin doctor Lynton Crosby had sent Shapps an email in August 2014 about Clarkes use of a job title.

The inquiry report said: “Mr Shapps’ initial response stated that they were all well aware of Mr Clarke’s reputation. He added that Mr Clarke’s candidate file made interesting reading, but that the view had essentially been taken that Mr Clarke was a difficult individual who delivered.”

However, the lawyers said there was no evidence that Shapps or Feldman had been made aware of the allegations of bullying or harassment before August 2015.

Johnson’s father, Ray Johnson, promptly branded the report a “whitewash”, telling Channel 4 News [1]: “We knew in our hearts it would be nothing more than a cover-up. They’ve exonerated themselves.”