Client Success Partner (12-month FTC) in London

About WPP WPP is the trusted growth partner for the world’s leading brands. We unite cutting-edge media intelligence and data solutions, world-class creativity, next-generation production, transformative enterprise solutions and expert strategic counsel in a single company – powered by exceptional talent and our agentic marketing platform, WPP Open, to help our clients navigate change, capture opportunity and deliver transformational growth.

The opportunity: A commercially astute and consultatively minded Client Success Partner to join our client leadership team. This is a senior advisory role at the heart of how we create value for our clients — translating complex analytical work into strategic guidance that directly shapes our clients' investment decisions and growth trajectories. You are a trusted advisor first and foremost — someone who builds genuine partnerships with senior client stakeholders, earns a seat at the table through deep expertise, and brings the intellectual curiosity and commercial instinct to identify where Gain Theory can make a meaningful difference. You will bring 12+ years of experience in marketing effectiveness, analytics, or a related consulting discipline.

What you’ll be doing:

• Acting as a Strategic Advisor to Senior Clients: You'll be the primary consultative voice for your clients — proactively shaping how they think about marketing investment, effectiveness measurement, and growth.
• Translating Complexity into Strategic Clarity: You'll take sophisticated analytical outputs and craft compelling narratives that resonate with senior decision-makers.
• Shaping the Consulting Agenda: You'll lead strategic client conversations, facilitate workshops, and contribute to thought leadership.
• Identifying and Developing Client Opportunities: You'll proactively identify where expanded consultancy can add value — growing relationships organically through relevance and trust.
• Enabling a High-Performing Consultancy Team: You'll lead and mentor a team, fostering a consultative culture built on intellectual rigour, client empathy, and continuous learning.

What we want from you:

• Analytics Consultancy Expertise: A proven track record of advising senior stakeholders and delivering recommendations that influence real strategic decisions.
• Deep Analytical Fluency: The ability to engage meaningfully with sophisticated analytical methodologies.
• Trusted Relationship Building: Demonstrated success in developing genuine, long-term advisory relationships.
• Strategic & Commercial Acumen: Experience identifying growth opportunities through consultative insight.
• Industry Knowledge & Intellectual Curiosity: Deep grounding in marketing effectiveness and analytics.
• Values Alignment: A natural alignment with core values: Be Curious, Be Positive, Act with Consideration, and Make it Better.

Your Impact Will Be Measured By:

• Depth and quality of strategic advisory relationships with senior client stakeholders.
• Demonstrable value and strategic influence delivered to clients.
• Exceptional client satisfaction.
• Achievement of net sales growth targets through consultative opportunity development.
• High satisfaction and consultative capability growth within your Client Success team.

Key Relationships You'll Build:

• Senior client stakeholders (Marketing Directors, CMOs, Insights and Strategy leads).
• Client Success Group & Executive Leadership Team.
• Gain Theory's Data, Analytics and Operations community, plus New Business and Strategy teams.

Location: Ideally London, with an expectation of 2–3 days in Gain Theory and/or client offices.

Why work for us? Gain Theory is committed to actively building a diverse, equitable and inclusive workplace where everyone feels welcomed, valued and heard, and is treated with dignity and respect.

What we pride ourselves on:

• Growth and development.
• Meaningful work.
• Flexible by design.
• Brilliant benefits.
• Culture with Heart.

Who we are: We are a people-centric organisation whose culture is underpinned by 4 important values: Be Curious, Be Positive, Make it Better and Act with Consideration.