Further with regard to the "as far as it is possible to do so" clause, in the Children Missing from Education section of the Education Bill, this probably refers also (apart from the Data Protection clash) to the funding crisis in the various departments that would be tasked with finding these kids.
There are reports of significant deficits in social services departments, for example, though goodness it is hard to find a clear declaration that this is indeed the case. I personally can't be sure that I'm reading the Audit Commission's accounts correctly. If anyone can look at this from page 57 onwards, not nod off and make sense of it for me, I would love to hear from you.
Am living in hope that the considerable expense of enacting the legislation requiring the tracing of children missing from education will be prohibitive and that we may therefore be left alone.