With its cockpit and engine commonality with the Comet, did the Caravelle ever figure in Dan Air plans? Perhaps the Comets were so readily and cheaply available, that it was just easier to operate this jet type before the 1-11's became available
MEA seems to be the only airline I can think of who operated the Caravelle and Comet side by side
Caravelle needed an FE, same as the Comet, so being a smaller aircraft there would be little cost advantage.
I think Aerolineas Argentinas were the other Comet/Caravelle buyer. Egyptair had several leased long-term from Sterling in the 1970s which ran together when the Tu154s, bought to replace the Comets, were sent back within months and some leased capacity was needed to fill the gap.