The final two-week delay to closing the RHI scheme – which Sinn Fein claimed credit for securing – was projected to cost taxpayers £91.5 million, the inquiry has been told.
By that stage in February 2016, the scheme was operating with cost controls but there was still a sense of urgency about closing it, given the mounting cost to the taxpayer.
Contemporaneous emails show that senior Sinn Fein figures were claiming credit for the two-week delay.
Mrs Foster admitted that when the scheme was finally closed a decision had been taken by the DUP and Sinn Fein – without consulting the other Executive parties or taking detailed advice from civil servants about the potential cost – to delay closure for two weeks.
The two-week timeframe was effectively plucked out of thin air, she admitted, amid negotiations between DUP and Sinn Fein Spads – a form of “brokerage” which she suggested was commonplace under devolution.
The cost of that decision will be slashed if the courts uphold retrospective cuts to subsidies which have since been made by Stormont.
Given that the DUP and Sinn Fein jointly agreed that approach, Mrs Foster said that “we have to take that on the chin”.
The former first minister also told Sir Patrick Coghlin’s inquiry that the late deputy first minister Martin McGuinness was aware of a whistle-blower who in January 2016 approached her with a series of allegations about how the scheme was being abused.
The note claimed people were abusing the RHI scheme by running boilers 24/7 and all year round for financial gain and in some cases heating empty sheds.
Senior Sinn Fein adviser Aidan McAteer has claimed to the inquiry that the note “was not shared” with Mr McGuinness “at that time”.
Mrs Foster said she was clear that if she did not give it to Mr McGuinness, she spoke to him about it.
In any event, she said, by sharing the note with the head of the civil service – who worked jointly with the DUP and Sinn Fein – she expected it to be given to Sinn Fein.