Thanks for the replies.
Looking at the FRADU Canberra web-site it seems the last one was withdrawn in 1985. So I'd have thought it unlikely this photograph was taken during the SS Canberra last trip which was 15 years ago this month...1997.
Definitely post Falklands though as she has the Falklands shield fitted above the Bridge windows. So between 83-85 would be my guess.