Although a bit off-beam here, but hey - Rob, hope that you won't mind?

Rod, when ships became STUFT - did they then become HMS, for the duration of the time they were in service for HM Gov't?
Also when QE2 was STUFT, although her designation remained unchanged in 1982, do you know whether either she or Canberra had their call-signs changed for security purposes?
btw - thank you for your kind of 'trying' - it works well!
Rosie