The Speedbird logo was designed for Imperial Airways in the early 1930s by a chap called Theyre Lee-Elliott, who when at Cambridge (reading Theology of all things) had spent much of his time on sports, being a tennis Blue and an England table-tennis champion. Didn't become a vicar but instead a freelance artist, where he picked up a considerable number of commissions, including the Imperial logo and name, which has certainly stood the test of time. It may be the oldest airline branding of all still in use.
Although BA don't use the graphic much now there is a permanent reminder done in the tile-work of Hatton Cross Underground station, next to the BA maintenance HQ.
https://en.wikipedia.org/wiki/Theyre_Lee-Elliott