I have banged on about this ad infinitum, but am happy to do so once again.
The CPS brings a case if it believes it has a reasonable chance of conviction.
If the evidence which is revealed - and that can only be revealed after investigations as a result of a charge being raised - results in a decision that a conviction is unliekly, then the case is dropped.
It's a pure Catch 22 situation - you can't get the evidence for a court case until you bring a charge, you don;t know if the charge will stand up until you examine the evidence that the charge has revealed.
So the notion that the CPS chuck charges about in the hope that the odd one will stick, or that the person whose charges are dropped is completely innocent of anything, are eronious.
The CPS will inly invest public money in a trial if it believes there is a better than average chance of a conviction - in other words, being able to prove what they know beyond a reasonable doubt.
If that beief is not there, the charges are dropped, but that simply means that the CPS knew enough to raise a charge, but they don;t have evidence enough to be sure of proving it in court.
Knowing something and proving something are different - and that is the cornerstone of British justice.
It does not mean that Mr Gambaccini is innocent - merely that insufficient evidence (and that's not the same as no evidene) exists to pursue a trial in a reasonable hope of a convction.