More tests will be needed to determine exactly why a senior Conservative and personal friend of David Cameron died in a portable toilet at the Glastonbury Festival over the weekend.
Christopher Shale (56) collapsed just after being warned that a private strategy document he had written for the party had been leaked.
There is no evidence that the news contributed to what is thought to have been a massive heart attack. At the opening of an inquest yesterday, the cause of the death was recorded as "unascertained".
However, Mr Shale's stepson Edoardo Mapelli Mozzi told the Daily Telegraph his family were certain Mr Shale had died of a heart attack.
"We have been told that it is 99.9% sure that he had a heart attack. But they want to do the extra tests because of the publicity around the case," he said.
Mr Mapelli Mozzi added: "He was a father to me, the only father I have ever known, and a father to all three of us - the best father we could ever have."
A source close to Mr Shale's widow Nikki told the Guardian that on Monday evening "he hadn't been feeling great" on Saturday. This was before he responded to the story which would shortly appear in the Mail on Sunday.
One effect of the death has been that Mr Shale's last political document, meant only for the eyes of a few hundred paid-up Conservative Party members , is now being read by thousands.
In it, he warned of a widening difference between party activists and Conservative voters. Potential supporters are put off joining because they fear they will face never-ending demands for money, and will be expected to take part in activities that do not appeal to them, such as door to door canvassing, he claimed.
Others suspect that sheer inefficiency is a part-cause of falling membership. Mr Shale suggested that the way to stop the shrinkage was to organise imaginative social events so that being a party member would be more fun.