Classify the relation of question with context to one of these categories: 1) award received, 2) based on, collection, 3) conflict, 4) constellation, 5) convicted of, 6) date of death, 7) director, 8) drafted by, 9) educated at, 10) medical condition, 11) military branch, 12) narrative location, 13) occupation, 14) original network, 15) parent company, 16) point in time, 17) production company, 18) residence, 19) series, 20) service entry, 21) sex or gender, 22) spouse, 23) standards body question.

Context : After TUI UK merged with First Choice Holidays in September 2007, it became part of TUI Travel PLC. The new holiday company continued with both in-house airlines (Thomsonfly and First Choice Airways) through Winter 2007 and Summer 2008 until the two were merged on 1 November 2008 as Thomson Airways. 
Question : What is Thomsonfly's parent company?
parent company