I am aware of a similar situation earlier this year, where a RTF examiner, rather than a FE, had inadvertently let their authorisation lapse. The CAA rejected an application from another school's student when we had someone about to send their's off. I believe that once the examiner had submitted his renewal paperwork and fee, his authorisation was renewed and the customer's PPL was issued, our student just sent his off a couple of weeks later. As far as I'm aware, there were no retests done.