The "Double Sunrise" service between Perth WA and Colombo, Ceylon was a service managed by Qantas in the latter half of WW2. It was used as a link between Australia and the rest of the British Empire (India, East and South Africa, etc). Wikipedia says it was part of an air mail link to Britain, but that is not correct as the mail route had been broken across the Mediterranean. However, it did connect with the remnants of the BOAC "Horseshoe Route", operated by Short Empire aircraft, from Colombo through Cairo to Durban in South Africa.

The Consolidated Catalina, built initially in San Diego at the same plant that later did the Convair twin props, and later by other plants in the US and Canada, was the longest range aircraft around at the time, being a flying boat it could take a huge long run unrestricted by runway length and thus carry a big fuel load. The Australian Air Force RAAF got a good number, but had no experience at first of long overwater flights, so Qantas brought them from San Diego/Honolulu to Australia, and when the Double Sunrise started it was determined that civilian crews would be required, which used this experience. Contrary again to a number of accounts, the five Catalinas used were not Australian, but British, taken from the Royal Navy and operated with British civil registrations. The route passed within range of Jap air patrols from Indonesia, but passed through those areas at night; the existence of the operation was kept secret. Total airborne time was about 28 hours westbound. All five Catalinas survived the war. Later their routing was extended from the Colombo stop to Karachi, as BOAC were so short of pilots.

Here's a map and a certificate

https://ww2aircraft.net/forum/thread...sunrise.34006/

In my library is a book "Croissants at Croydon" by the onetime General Manager of Air France in Britain, Jack Bamford, at London Croydon airport and elsewhere, right from the start in 1920 until he retired in 1960. When WW2 came along and the French service to Britain stopped he went into the RAF "for the duration" as was the British expression of the time, and ended up managing the Return Ferry Service that took pilots who delivered all the US-built aircraft to Britain back across the Atlantic. When Churchill visited Roosevelt in Washington (by ship) after Pearl Harbor there was a clandestine operation in darkest winter December 1941 to take government mail to the meeting, Bamford had to organise this then go with it, and took a Catalina from Prestwick to Halifax in Canada. His book has a fascinating extended description of the flight, also over 24 hours, including all its organisation, which (apart from all the icing issues) gives a good flavour of these huge overwater expeditions that the Cat was capable of. The whole book is a great account of 1920s-30s airline operation, up to this Catalina flight.

https://www.abebooks.co.uk/Croissant...12495215236/bd