Former Stormont first minister Arlene Foster: was asked  why her then special adviser, Dr Andrew Crawford, had not read expert reports related to RHI options and why Fiona Hepper had not endeavoured to record notes of the encounter.  Photograph: Yui Mok/PA

The chairman of a public inquiry into Stormont’s “cash for ash” scheme has questioned whether a key department run by Democratic Unionist Party (DUP) (...)