You might find this interesting. http://www.farvis.com/ventnor2.htm
Some of the smaller British airlines were formed after the end of WWII, typically by ex-military pilots who suddenly found themselves out of a job. Most were run on a small budget & often used ex-military aircraft that were available at knock-down prices after the end of the war. The C-47 (Dakota) was an obvious choice. There were plenty on the surplus market & these could be easily converted into airliners. The proper C-47 with large double-doors & strengthened cabin floor was ideal for cargo. Some examples, like ZB in the article, had previously been used as military transports by the RAF & possibly didn't need much in the way of conversion. Channel Airways Dakotas were once a common sight at my local airport.
The BEA version, named the Pionair, was a considerably modified DC-3/C-47 & used many non-standard parts. I remember back in the 60s that the company I worked for manufactured some of these parts. I'm not sure what happened to the drawings or the special tools involved but suspect they were eventually scrapped. I recall that at least one of the original Air Atlantique fleet was a Pionair. I helped trace some of the special parts for it but it's extremely difficult & expensive to supply non-standard parts for vintage types. Much easier to convert back to standard if possible.