Didn't know there was a Comet with the title 'Canopus' too. I was with 99 Sqn which flew Britannia's from 1959 onwards and one of the RAF Britannias had the name 'Canopus'. This was XN404 a C.Mk 2 and I see from my log book that I first flew in this on 20th October 1959.
Two photos of Brit XN404 courtesy raf-transport-command-veterans and XM496.com