I have eaten in two reiterations of the Caronia.
Columbia, then Mauretania and finally
The restaurants were named as follows:
CURRENT CARONIA
Columbia Restaurant (1969 - December 1994)
Mauretania Restaurant (December 1994 - April 1997)
Caronia Restaurant (April 1997 - today)
CURRENT MAURETANIA
Britannia Restaurant (1969 - December 1977)
Tables of the World (December 1977 - April 1987)
Mauretania Restaurant (April 1987 - December 1994)
Caronia Restaurant (December 1994 - April 1997)
Mauretania Restaurant (April 1997 - today)
The change in 1994 was to move the former first class restaurant to a higher deck - aspirational etc and share the bar facilities with Grills. QE2 was 'classless' from 1995.
The change is April 1997 was done to appease those regular Columbia passengers who complained about the loss of "their" bar (Midships Bar / Chart Room). They did not like having the Crystal Bar forced on them!