Quadri was most recently managing director at market research agency PDI, and has spent over a decade in project management and operations, having begun her career at Ipsos Retail Performance.

Brown was previously global research and insight director at MetrixLab, and has also held roles at KPMG Nunwood and MMR Research.

Both Quadri and Brown will be part of Irrational Agency’s senior team and based in its London office.

The company said the appointments follow ‘significant year-on-year growth’.

Stephanie Shaarwi, managing director, Irrational Agency, said: “Sonia is an extremely experienced operations professional and will be spearheading our drive to build on our operational excellence.

“Helen’s wealth of experience at as a senior researcher will be invaluable as we continue to enhance our existing quantitative capabilities and deliver impactful insights to clients.”