In order to be confidential information the information must have the necessary quality of confidence.
In the case of Saltman Engineering Co Limited v Campbell Engineering Co Limited  65 RPC 203 it was stated that in order to be confidential the information must: Â
“have the necessary quality of confidence about it, namely, it must not be something which is public property and public knowledge.” (ignoring of course situations where the information is considered as confidential by way of contract)
For certan siuations it is obvious that information is confidential for example where a secret recipe is used however where the information is not too different from information that is already in the public domain some disputes can arise. The basic rule is that in order to be deserving of protection someone must have added some thought and effort to information that is already available in the public domain: Coco v A N Clark (Engineers) Limited  RPC 41 where Megarry J said: “…whether it is described as originality or novelty or ingenuity or otherwise, I think there must be some product of the human brain which suffices to confer a confidential nature upon the information.” Â
An important point to appreciate here is that just because you describe information as being confidential it does not mean that it is, the best defence is simply to not disclose information although of course there are situations in which it is neccessary to do so. In these cases a well drafted confidentiality agreement can give some comfort but simply if the information does not have the neccessary quality of confidence then it will be difficult to protect. Even encrypted infromation will not neccessarily be confidential as “anyone with the skills to de-crypt has access to the information” (Mars v Teknowledge  FSR 138).