The answer is when the case is dropped by the CPS due to no evidence (not insufficient evidence) but then the exact same allegation is 'tried' in a professional hearing. Tried to a lower threshold of evidence to a panel all too willing to hang on to every word of police allegations. I know because this recently happened to my partner.
The police in their cocky arrogance just simply repeated their allegations, including their 'intelligence' which was profoundly wrong, added some salacious titbits of opinion and dressed up normal activity as hiding illegal activity. The panel simply sucked it all up, ignoring completely any evidence supporting innocence or suggesting anything other than guilt. Two careers destroyed, and two people dragged through the mud and contemplating suicide. As you can see it annoys me slightly!
In my opinion these 'hearings' have become a back door for failed prosecutions and offer no protection for the defendant. They are even posted on websites in all their glory for people to drool over. A bloody Kangaroo court with no standards whatsoeve.
Anyway...feel better for that!