I too passed my ATPL exams but then lost the validity as I couldn't get the flying done within the required time for medical reasons.
I have been thinking about giving it another go but always thought I would have to do the full course, brush ups, it didn't occur to me that I might not need to do full course until I read this post.
However the exams were done a while ago though, 2007 with Oxford and I imagine things have changed a bit.
Who decides if I have to do full theory course again? the CAA ?