Unless I am having complete false memory syndrome, were there not subsequent marine turtles kept at London in the Aquarium? I remember seeing theum as a child but wasn't born in 1984!
You are definitely correct! I was about to query this myself, as my first visit wasn't until 1989, and I have photos of sea turtles subsequent to that. I believe they were Green Turtles.
Checking the ZSL Annual Reports confirms my earlier comments that the green turtles and loggerhead turtle left London Zoo, for Blackpool, in 1984.I was thinking exactly this.
However London Zoo retained its hawksbill turtles until 1996 when they were sent to Sea World of Florida. These were presumably the marine turtles others were talking about.