Entourage: New Advisor for Mathilde

24 July 2026

Quite a landslide in the Belgian Queen's entourage has happened as Mathilde's main advisor, Machteld Fostier (68) who's been with her since 1999, has retired. In September 2026, at the start of the new royal year, she will be replaced by Marleen Steenbrugghe.

A skilled and experienced diplomat, Machteld Fostier was with Mathilde from her very first days on the royal scene. For years she was the Princess's only close collaborator, they worked together daily. Wherever Mathilde went, Machteld was present - both at the office and during public activities in Belgium and abroad.

During a two year break, from 2006 to 2008, Machteld Fostier didn't work for Mathilde, but was the Belgian Head of mission in Washington. In 2009 she took up her former position again. When Mathilde became Queen in 2013, Machteld stayed in place, from then on with the title of private secretary.

Just like Mathilde, Machteld Fostier has been a very loyal and dedicated worker, a perfectionist. 

Over the years the two women seem to have become personal friends. When King Philippe was running the 20 kilometers through Brussels in 2014, Machteld came along with Mathilde and the children to cheer him on. She's also known to have selected children's clothing for the princes and princesses when Mathilde was too busy with work.

Machteld Fostier is succeeded by Marleen Steenbrugghe (40) who previously worked as an advisor on multilateral affairs in the cabinet of Minister of Foreign Affairs Maxime Prévot. 

Steenbrugghe studied law and holds a master's degree in international relations and conflict management.

She began her diplomatic career in 2009 and gained experience at the Permanent Representation of Belgium to the European Union, the Belgian Embassy in Thailand, and at various international institutions in Geneva. Between 2015 and 2020, she worked at the Belgian representation to the United Nations. Subsequently, she served for five years with the European Union delegation in Geneva. 

Machteld Fostier will remain at Mathilde's disposal for certain special activities.