My smug feeling was soon overturned this morning when I found flakes of primer coming off in my hands! Apparently the panel wipe I had used on the bare metal is meant to be left for at least 30 minutes before painting. Of course I'm always in a hurry and left it about five! Result is the primer pops. Spent this morning rubbing it all off again and this time used no chemical wipe down, just a scratch up with some emery and this time used an etch primer. Wont be making that mistake again.