Yes, I think this is the case. Even after all those years you could tell she was annoyed giving evidence and more than likely annoyed at having to remember the initial story they concocted. She probably thought she would never have to replay their version again after so long. The fact she dragged McDowall out of the police station in the 1970s and the slip of the tongue mention of "stabbing" in a later interview leads to the likelihood she knew and covered for him.
