Pembrokeshire coroner Mark Layton will issue witness summons to the chief executives of both the Welsh Ambulance Trust and Hywel Dda Health Board, after a crucial report and a health board representative failed to show up at a pre-inquest hearing on Thursday.

Mr Layton had expected a representative from the health board to attend the hearing into the death of Wayne Anthony Young on January 1 this year. He had also been told that an investigation report would be available by the end of May.

"I am very disappointed that no one is here," he said. "I wanted to know what was going on."

Rhiannon Rees, a solicitor for the health board, said that the report was currently with the Welsh Ambulance Trust who needed to undertake "deeper investigations".

Investigations were ongoing into the relationships between control desks in Carmarthen and North Wales and responses were being co-ordinated from other agencies.

"It has proved more complicated," she said. "They don't want to produce a knee jerk reaction." She said the investigation would have "far reaching consequences for the service" and new policies would be drafted as a result.

She added that the health board had completed their part of the report and expected to have the document back by the end of July. The completed document should be ready by mid September.

Helen Cradick representing Mr Young's family, said: "From the family point of view they want to know what happened to their father," she said. "In the short term that's what the family want to know. In the long term they will be pleased to know changes will be made."

She added that the family had still not even seen the medical reports.

Mark Layton ordered that by next Friday both the family and the coroner's office should have copies of the medical notes.

He said that the next hearing would be in mid September and by that date he expected the report.

"I will be preparing a directive for the chief executives [of the ambulance trust and the health board] to attend," he said. "I will waive the enforcement of that if somebody with working knowledge of the report attends the next hearing.

"When we ask someone to come along voluntarily it's to avoid serving witness notices and witness summons. If somebody does not attend, witness notices and witness summons will be served."