In reply to Roadrunner5:
It certainly is !!
I remember in 2014 when Paul Giblin took an hour off the long standing record ( 15:26 in 1989 ) with a 14:21, and everyone was amazed, he shaved a few more minutes the following year to 14:14, and now those have been obliterated.
With all respect to Rob, you have to wonder what time could be possible if Kilian or Luis Alberto Hernando, or Jim Walmsley, etc gave it a go. I know it's unlikely to ever happen, but I'm guessing it would start with a 12 ??