It may well be just me, but I think we saw the Jason Beer strategy here. Start off by letting them talk. Witnesses come with pre prepared and rehearsed answers, so just let them speak and trot them all out.
Eventually they run out of prepared bull shit and have nothing left to say. Once that happens, hit them with direct questions about things like why did you arrange a job for someone who worked for your husband, why did you use personal / political contacts to try andinfluence BBC?
Refusing to cooperate with TV investigation, and then complaining that the programme was one sided is certainly imaginative.