There is a limited paper-trail between DUP special advisers during a key phase of the RHI debacle when it was alleged they were thwarting attempts to delay the introduction of cost controls, the public inquiry has been told.

Most of their communications were over the phone or in meetings which were not minuted, RHI Inquiry counsel David Scoffield QC told the panel.

The inquiry has begun to look at the summer of 2015 when the scheme was running out of control and attempts were made to stem the flow of money.

A central allegation made by former DUP minister Jonathan Bell is that he was thwarted in attempts to close the scheme by a number of DUP special advisers (spads), including Timothy Johnston and Andrew Crawford.

‘Highly contentious’

At the time, Mr Johnston was adviser to the then First Minister Peter Robinson.

Mr Crawford was working in finance with the then minister Arlene Foster.

Both men have denied the allegation and Mr Scoffield said much of Mr Bell’s evidence in respect of this period was “highly contentious”.

The inquiry has checked personal email accounts of key participants in this period and, where available, had mobile phones analysed.

But in most cases, Mr Scoffield said, the information did not go as far back as 2015.

‘Phones wiped’

He said in some cases this was because people had cleaned out their inbox.

They may also have handed back departmental phones which were wiped and passed to other civil servants.

“I think it’s fair to say that there’s less of a paper-trail in terms of relevant communications between spads than this inquiry would have liked to have seen,” Mr Scoffield said.

He said as a result of the lack of supporting paperwork the inquiry would be heavily reliant on the witness statements and oral evidence of the special advisers who would be called to give evidence and its assessment of what it heard.

Mr Scoffield said if special advisers or others had been engaged in “anything improper or on the fringes of what they knew to be permissible” and which might be embarrassing for them or their parties, that might provide an incentive to ensure “that less rather than more was recorded in recoverable form”.

He said the inquiry might want to consider whether among special advisers and civil servants there might have been a practice to ensure that “embarrassing or controversial material” was not placed on the formal record.