The ICPC is a scheme, not something that is mandatory yet. Although I think it should be.

However a CRB is just as effective, although to my knowledge doesn't make use of CEOPs databases. A CRB should be run every time a person applies to work with children... And is required by law in the UK if you are applying to work with children or vulnerable adults. In time it may be that the ICPC completely replaces the CRB, but for now it is an opt-in scheme.

If you are 'hiding the fact you are a paedo' neither a CRB nor the ICPC will be of much use; that is the very point of hiding the fact. If you are logging on from a internet cafe, or from an anonymous public wifi source, CEOP are unlikely to find you in their databases either.

Running a criminal check on anybody entering a foreign country to live and work (especially in a position of authority such as teaching) is normal and nothing to worry about if you have nothing to hide. It certainly shouldn't be viewed as a "bloody criminal background check" as if it's troublesome to you. If you have reason to view it as such, to me that's a good indication that you have something to hide.