Grass Roots' Tring-based events operation is being moved to Marlow to work under the Maritz brand.
And Grass Roots operations director Mark Taylor has resigned and been recruited by rival agency BI to head up its events team.
The Grass Roots team of ten events staff will operate under the Maritz brand and be overseen by Maritz managing director Nick Bender from 8 September. The move will mean there will be a 260-strong events staff working under Bender.
Grass Roots Group chairman David Evans said: "We have a centre of communications and event management expertise in Marlow and I want to build on that. This is all about playing to our strengths. Existing clients that were being served out of Tring, will now enjoy the support of a much bigger team of specialists in one location."
Meanwhile, Taylor, who has worked for Grass Roots for some 18 years and is the Eventia vice chairman, will take on the role of head of events for BI on 1 October. His remit is to develop the 30-strong events team, which manages some 100 events a year for corporates including Peugeot, BMW and GM. Grass Roots maintains Taylor's resignation is unrelated to the move to Maritz.
Evans continued: "Mark has been a fantastically loyal servant to Grass Roots and is one of the most professional operators in this industry. He feels the time is right for a change of scenery and I fully respect that decision. He leaves with our gratitude and very best wishes for the future."
Taylor said of his move: "BI has had a very successful few years and I am excited to be part of this expanding and energetic company. This move brings with it a new challenge for me, but I am confident that working closely with BI's professional and enthusiastic events team we will continue to build upon its success."
BI managing director Richard Bandell added: "Mark brings unparalleled expertise and knowledge to the business, and we are pleased to welcome him to BI."
Taylor will replace BI commercial director Stuart Warwick, who has been responsible for BI's events team for the past 18 months. Warwick will move into a new role with a remit to develop of BI's overseas business, which includes its China-based agency Mint.