OK I read in and regex parsed wx_gamelist.cache, lots of hoops to jump through to make it fast with lots of entries but got there in the end. Hopefully the regex will survive wx_gamelist.cache file format changes between versions of Dolphin, if the format ever changed to xml that'd be handy. Yes "MaxPlay Classic Games Volume 1.gcz" did catch me out! 
Thanks for your help

Thanks for your help