Separately, Keith Betton, ABTA's outgoing director of corporate affairs, is to join Siren as a part-time associate director.
Siren MD Rachel O'Connor is seeking to build its travel-brand portfolio, which includes Royal Caribbean Cruise Line and Daytona Beach. Siren has seven staff and an annual fee income of £500,000, with Kellogg's and NatWest also among its clients.
Luton-based TUI, which will sell 4.5 million holidays this year, has yet to announce a replacement for O'Reilly, who was promoted to a board role in May (PRWeek, 5 May).
O'Reilly, who joined TUI in 2000 from travel PR agency BGB, said: ‘I wanted to broaden my experience, and there's scope in the consultancy market to combine big-brand thinking with travel industry expertise.'
Betton leaves ABTA in December, having overseen the 2006 convention in Marbella, the UK travel industry's best-attended event.