Field-Marshal Mogau knew it was Donna, the Doctor… Mr Lewis’ niece. When she was asked where she was at the time of the robbery, she stated she was ‘hauling in a big trout.’

But Donna was supposedly out on the water at the time, and so (unless she had guilty knowledge) she could not possibly have known at what time the robbery was committed.

Donna, the doctor, fell directly into Field-Marshal Mogau’s trap…