Source: p 186, The Art of the Advocate (1993) by Richard Du Cann QC (called to the Bar of England and Wales).
Until then great attention will be paid to any question asked by the jury on the nod and wink principle referred to. Counsel will do anything they can to answer, or to explain why they cannot answer, the question that is put. Some can be very embarrassing. The one cited in the last paragraph
[1.] [(for instance, in a criminal trial, 'has the defendant done this before?')] [herefrom]
[2.] would probably lead to the discharge of the jury if the defendant did have any previous convictions
[3.] since by refusing to answer the question the jury would be bound to infer that he had, thus taking from the defendant his right to anonymity of character.
To me, 3 appears to be the Logical Fallacy of Appealing to Ignorance. So how would 3 imply 2? A refusal to answer the question does not logically imply a negative answer, though I understand why one may infer so.
What if it is the Judge who stops and prevents the witness from answering 1? Then the jury cannot infer anything about the witness.