A former DUP special adviser has said a Northern Ireland government department should have had more experts to run a renewable energy scheme.
John Robinson said there is a lesson to be learned from the botched Renewable Heat Incentive.
Costs for the scheme in Northern Ireland spiralled due to over-generous subsidies for using biomass boilers.
Anger at how costs soared led to a political row and the collapse of powersharing institutions at Stormont.
A public inquiry set up to examine what went wrong has heard allegations that special advisers acted to delay cost-cutting measures in 2015.
Mr Robinson, who was a special adviser in the Department for the Economy in 2016, has denied he was involved in alleged efforts to delay the measures.
Asked what lessons he felt could be learned, Mr Robinson told the inquiry: “The expertise was not in the department, the experts who were needed to manage the scheme but also to develop the regulations.”
Mr Robinson said he and economy minister Simon Hamilton frequently met stakeholders with more expertise.
He said civil servants in the department were not getting the time to read into an issue and become an “absolute expert”.
“They were very sincere people and working hard, but that was not their expertise. In a year’s time they could have been working in DFP (Department of Finance and Personnel),” Mr Robinson told the inquiry.
“Maybe the lesson out of RHI is if you have experts you may actually save money.”
