Graham is right about the Britannia 320s. They operated some flights in/out of BRS in the summer of 1999 along with the based 757. The 320 may well have been based for part of each week that summer.
From memory they were painted in the Britannia livery of that period although I have a vague memory that it was not a complete Britannia livery. I may be wrong on this point.
BY operated about 25 weekly flights that summer compared to Air 2000 (First Choice) at around 16. As WATABENCH has said, FCA have certainly forged ahead since then.
In checking old timetables etc I find that BY operated a fortnightly 767 flight from BRS to Orlando in summer 1995 (or it may have been Sanford if BY used that airport then), undoubtedly via another airport because of the R-word.
I seem to remember Britannia flights to the Dominican Republic some time in the 1990s but only about three one summer. I believe it was a year when Thomson decided to operate to that part of the Island of Hispaniola from several UK airports not normally associated with such flights, but only two or three from each airport.