At WCRS, Marsland will report to the chief executive, Matt Edwards, and form part of the management team that also includes the executive creative director, Leon Jaume, and the executive planning director, Matt Willifer.
In the new role, Marsland will be responsible for new business and marketing, as well as running key accounts.
Before Tesch, Marsland worked at Wieden & Kennedy for eight years, overseeing new business. She was also the business director on accounts including Nike, The Guardian and Nokia UK. Marsland previously held positions at Made, Euro RSCG, TBWA\London and Ogilvy & Mather.
Edwards said: "The new-business market has never been so competitive, so it's great to have someone with Emma's skills and experience join the WCRS team."Follow @SaraKimberley