It’s hard to imagine aircraft having ungainly square windows - but they once did.

It was not until late into the Fifties that the round or oval cabin windows we all know and love were introduced, and it was not merely for aesthetic reasons.

Kitted out with square windows, the de Havilland Comet was the world’s first commercial jetliner. First flown in 1949, it was set to revolutionise air travel for millions.

At first, the Hertfordshire-made aircraft lived up to the hype, carrying 30,000 passengers in its first year, including Queen Elizabeth, the Queen Mother and Princess Margaret, guests on a special flight in 1953, hosted by Sir Geoffrey and Lady de Havilland.

Its engines allowed the Comet to fly higher than its competitors, above 30,000 feet, increasing speed by as much as 50 per cent as well as avoiding bad weather.