Aussie A, the current security situation makes it an SOP for most operators to monitor 121.5 as much as possible, even over the UK. It is a distraction to have to listen to practice PANs etc but on the other hand it is recognized that such practices are invaluable for students and D&D controllers alike. The UK is almost alone in using 121.5 for practice purposes and, I believe, has had to file a Difference with ICAO for this. It's a bit like using 999 for practice emergency telephone calls. The answer to satisfy both requirements is to have a practice emergency frequency, I think the UK military have got one on UHF so it's not an unknown concept.
(Flew G-BIOM in the 1980s myself but never went that far in it!)