Principal Data Analyst (Hiring Immediately) in London

The opportunity: As a Principal Data Analyst, you will join the Gain Theory Data Practice and be embedded within one of our client-focused squads. Working closely with your manager, you’ll collaborate on some of the world’s top brands, gaining hands-on experience with diverse data sources—including media, client-specific, Gain Theory proprietary, sales, and more. In this role, you’ll be part of a team that processes and organizes data in preparation for modeling. You’ll face exciting challenges and have opportunities to drive innovation and automation across workflows.

As a Principal Data Analyst, you will apply data processing techniques such as SQL, ETL and Python alongside our internal automation tools, to manage, clean, and transform data through efficient pipelines. You’ll also run rigorous data quality assurance processes—ensuring data integrity, which is the foundation of all our work. Additionally, you’ll collaborate with the Data Manager to coordinate with client and agency partners, maintaining the continuous flow of data from key sources. Beyond your squad, you’ll engage with the wider Gain Theory data community, including the Data Centre of Excellence (DCOE), to share best practices and both provide and receive support. The Principal Data Analyst will also mentor and support junior analysts on their projects, helping them learn processes, best practices, and specific tools used by Gain Theory.

At Gain Theory, our teams combine cutting-edge data engineering, advanced analytics, unified measurement solutions, and enterprise-scale platforms to build products that will shape the next decade of faster, smarter, data-informed decision-making. We are committed to ensuring consumer privacy, safeguarding client confidentiality, driving brand growth, and delivering exceptional user experiences.

What you’ll be doing:

• Data Management & Analysis: Manage data extraction, manipulation and validation. Manage data extraction, manipulation, validation, and interrogation using SQL, Python, and other relevant tools. Build data QA insights relevant to the project. Ensure that all data is systematically checked and passes all QA steps.
• Data Architecture: Execute and update data pipelines. Build and maintain data ingestion and transformation pipelines using all the tools that Gain Theory has at your disposal. Build data ingestion and transformation pipelines using available tools, including Python scripting for data processing and automation. Work with fellow data analysts to build scalable solutions using ETL/ELT pipelines.
• Research & Development: Support wider improvements in data. Propose better approaches to help improve internal procedures including new methodology, etc. Share techniques and ideas with the wider data community.
• Meetings: Organisation and participation in internal meetings. Initiate and engage with internal project meetings, ensure there is an agenda. Ensure that project meeting action points are collated and shared with the team.
• Mentorship: Help guide and support junior members of the team. Guide and support junior analysts, providing training on tools and best practices.

What we want from you:

• Comfortable working with large amounts of data in a cloud ecosystem.
• Proficient with SQL and ETL processes, and experience driving robust QA processes.
• Experience with data interrogation, cleaning, and processing using Python.
• Snowflake experience a plus.
• Experience with data manipulation/visualization tools (e.g., Excel, Tableau).
• R experience a plus.
• Extreme attention to detail a must.
• Understanding or experience of business marketing and media a plus.
• Strong interpersonal and communication (written and oral) skills.
• Team-oriented attitude.
• Capacity to learn new skills and master new tools.
• Ability and desire to lead junior team members through mentorship and example setting.
• Can lead requirements gathering, project planning, and implementation of projects developed with DCOE leads.
• Has project management skills including planning tasks and deliverables, managing timelines and risks, managing team resource allocation, and overseeing multiple simultaneous projects.
• Ability to manage and motivate Gain Theory team members and to teach concepts or technologies that are developed.
• Organized, detail-oriented, QA-focused.
• Experience with DBT is highly valuable.

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. As leaders and creative partners across industries, it is our responsibility to cultivate an environment reflective of our greatest asset; our people. We believe that this commitment inspires growth and delivers equitable outcomes for everyone as well as the clients and communities we serve.

What we pride ourselves on: Growth and development, Meaningful work, Flexible by design, Brilliant benefits, Culture with Heart. Our exceptional and skilled team defines Gain Theory. That's why we seek individuals who strive for excellence and continually challenge us to improve.

What we do: Gain Theory is a global marketing effectiveness and foresight consultancy. Our vision is to accelerate growth for ambitious brands by giving clients the confidence to make better data-informed investment decisions. High-touch consultancy powered by unique partnerships and proprietary technology are used to power our award-winning solutions. As a WPP consultancy, Gain Theory also has access to a range of data, expertise, and tools that create a truly differentiated offering. Gain Theory is a WPP agency (NYSE: WPP).

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