First ever flight, Cambrian V.700 G-AMOO. Liverpool to Isle of Man. 4 engines for 85 nm. A few thereafter over the years, finally a surprise BMA V.800 one LHR-Teesside, a substitute for a DC9.
As I recall the F27 and Herald also had oval windows though not as big. Must have been a Dart thing !
I, too, have wondered whether these windows were actually the same stock item from the same glazing manufacturer.