The story
As part of a wider reorganisation of TUI's UK operations in September 2004, it was announced that Britannia Airways would soon be rebranded Thomsonfly. Thomsonfly changed its name to Thomson Airways in October 2008 after it started integrating with First Choice Airways, a process that was completed on 1 May 2009.
From Wikipedia’s article on Thomsonfly, shared under CC BY-SA 4.0.3
