//NJ - the law wasn't the same then. It was lawful to take a child out of school for 10 school days in any one school year but it's illegal now.//
You don't quit have the right end of the stick, diddlydo.
The offence has always been "failure to ensure regular attendance at school". "Exceptional Leave" (which would have been given for the ten days you refer to) would have been excluded from absences as they were authorised. All that has happened (since the 2013 guidelines were issued and the case of "Platt" was heard) is that schools have been given far less discretion to authorise absences and the Platt case clarified what "attending regularly" means. (Mr Platt argued that, apart from the unauthorised holiday she took, his daughter had attended school regularly).
It has always been a feature of English law that rulings in the High/Appeal/Supreme Courts set precedents for later rulings in the lower courts and they can be cited and used for decision making. The law itself does not change. The Platt case did precisely that (after a struggle all the way to the Supreme Court). Had the Supreme Court sided with Mr Platt it would have given carte blanche to parents to remove their children from school for a holiday provided they had attended as required for the rest of the time. Local Authorities then could have given up issuing Penalty Notices for such absences as their only redress if they were not paid would be court action in the Magistrates' Court. All the defendant would have to do (provided their circumstances were similar) would be to cite the Platt case to ensure acquittal.