Hearts & Science

For eight years, Tess LeGassick has been the planning force behind Hearts, shaping it into an agency where planning is central to success. As a founding member, she identified a critical gap and built the Connections Planning team from scratch, establishing planning excellence as a core discipline.

In Hearts’ formative years, Tess laid the foundations for a culture of planning brilliance, and she continues to raise standards to keep the agency at the forefront of innovation. Her impact was recognised in 2024 when she was named Campaign’s Media Planning Leader of the Year, as Hearts became the UK’s fastest-growing media agency. In 2025, Tess was promoted to Chief Planning Officer, expanding her remit to nurture talent, deepen strategic capability and champion more effective, creatively ambitious work. Under her leadership, Hearts delivered 42% organic revenue growth, increased headcount, doubled EBIT, secured four new clients and won its first Cannes Lion. Tess’s planning philosophy is rooted in practical application, using category entry points and attention-led thinking to drive growth. She created the Velocity framework and launched a craft-led training programme. Beyond planning, Tess champions culture and mentors talent. Her work has delivered over £1.2bn in revenue.