- Analysis by Vicki Hawthorne
A former DUP special adviser involved in a botched green energy scheme has claimed politics to be a 'grubby world.'
Timothy Cairns has claimed former enterprise minister Jonathan Bell behaved in bullying or drunken fashion at times and that he was so intoxicated he fell asleep in a New York pub and was asked to leave, allegations Mr Bell strongly denies.
Mr Cairns told a public inquiry he reported his concerns to former leader Peter Robinson but alleged Mr Robinson did nothing about it.
The ex-special adviser and lawyer admitted he was prepared to go along with the DUP's official version of events.
Renewable heat incentive (RHI) inquiry chairman Sir Patrick Coghlin asked him: "And that is politics is it?"
The witness responded: "That is politics I am afraid - it is a grubby world."
The retired judge said: "That is something of an understatement, if you don't mind me saying."
Mr Cairns concurred: "I think you are correct, Mr chairman."
He said he had not tried to smear the former enterprise minister over the closure of the scheme.
Sir Patrick said the "clear inference" was that the witness was prepared to modify his comments about Mr Bell to protect former DUP leader Mr Robinson.
The green energy scheme paid over-generous subsidies to wood fuel burner owners.
Concerns centre on how long it took to close after civil servants became aware of the flaws and the DUP's alleged role, if any, in manipulating that closure date.
The devolved powersharing institutions collapsed early last year after Sinn Fein walked out over the DUP's handling of the RHI and repeated rounds of negotiations have failed to resurrect them.
Documents before the public inquiry, including a text message from Mr Cairns to another party special adviser, showed the witness was prepared to, in his words, fit his story into the party's "narrative" around RHI.
Sir Patrick added: "That seems a rather unpleasant way to run a party."
Mr Cairns also suggested the DUP's chief executive, Timothy Johnston, delayed the closure of the RHI scheme to allow others to join.
He claimed DUP leader Arlene Foster knew about Mr Johnston's role in delaying closure, which she has denied.
Mr Cairns said Mr Johnston's influence was felt from the top to the bottom of the party. Mr Johnston is a former party special adviser who denied there was any hierarchy.
Earlier stages in the inquiry have heard there was a mistaken belief among those involved in designing the RHI that the Treasury would pick up the bill, so the intention was to have as many as possible enrolled to attract funds to Northern Ireland.
Mr Cairns has denied any plan to fit Mr Bell up.
Much of the former party official's evidence contradicted Mr Bell's version of events, discussed during the ex-Assembly member's colourful evidence sessions before the inquiry last week.
In written evidence, Mr Cairns claimed his minister, who was leading an Invest Northern Ireland trade mission, sang the Deep Blue Something hit Breakfast At Tiffany's at the top of his voice as he was helped back to his New York hotel after having drunk too much.