Beattie is leaving to join Cohn & Wolfe as London-based MD with European responsibilities (PRWeek, 13 Oct).
Helfer and Pleon Europe CEO Timo Sieg are to re-jig the UK structure, augmenting consumer director Eva Keogan's role with creative director.
Nick Morris is technology director, Craig Wildman will move from financial controller to finance and operations director, and Iain Halpin will become the agency's strategic consulting director.
Helfer said she would concentrate on growth across the agency.
Helfer joined Pleon UK as associate director from Firefly Communications in December 2004 with a remit to grow and develop Pleon's corporate and marketing offering.
As part of her role she was based for a time in The Hague with Pleon client Shell Renewables, Hydrogen and CO2 as interim vice-president of external affairs.
Helfer previously worked with SME Corporate Finance where she built a partnership of London-based services firms to support the growth of small technology companies.