Thomas's role is the most senior PR position within Reuters, covering media and investor relations, marcoms and internal comms.
Reporting directly into the executive board, the post heads a team of 24 in offices worldwide, including London, New York, Frankfurt and Singapore, alongside overseeing the group's agency roster, which includes Brunswick for City work in the UK.
Whoever takes over faces a tough challenge in boosting City confidence in a firm that has suffered heavy losses due to the economic downturn.
Shares in Reuters have fallen to 12 year lows this year and more than 2,000 staff have lost their jobs. This week it was announced that a further 300 jobs were being cut in the US.
The London-based corporate communications team has also been cut as corporate comms manager Adrian Duffield, who left to join agency College Hill & Associates last week, will not be replaced (PRWeek, 29 November).
Thomas said on the communications challenges facing Reuters: 'The key is - against a background of very difficult markets which we don't see changing in the short-term - to continue promoting the company and to communicate its strategy going forward in the simplest way possible, as it's a complex company.'
Following his retirement Thomas is planning to work as a charity sector consultant.