They were flown out of Southend airport and Lydd airport to Calais in France. It was a cross Chanel service before the days of RoRo shipping. Operated by a company called Silver City Airways owned by the Kegan family. Rupert Kegan dabbled in F1 racing as a private entrant in the 1970’s. The aircraft took 4 cars from memory and 20 passengers at the back, all unpressurised cold and drafty!!! Used them many times back in the day.