Originally Posted by ReelChief
While I wouldn't suggest changing the validator to accommodate it, I can confirm that MRU-LHR-...-LHR-MRU (with one as a transit) was being accepted and ticketed last month by BA. I don't know whether it has changed, or will be changed, once MRU-JNB is operational.
It has been reported here recently that it is no longer being allowed, because of the MRU-JNB flight.