BT Global — Design System
Building a single source of truth for one of the world's most recognised telecoms brands
The Problem
BT Global's digital products were growing faster than the systems governing them. Across multiple product teams, markets, and platforms, designers and developers were making their own independent calls on patterns, components, and visual language. The result was exactly what you'd expect. A patchwork estate, inconsistent, increasingly hard to maintain, and quietly falling short of the accessibility standards a global brand has to meet.
On the ground this showed up as a mix of outdated guidelines, locally adapted components, and undocumented decisions that had built up over years. For a brand operating at BT's scale, across global markets, multiple languages, and a vast range of digital touchpoints, this wasn't just a design problem. It was a strategic one.
My Role
I was brought in by TCS as an embedded Design Director within BT Global, sitting directly alongside BT's existing internal design and development teams. A deliberate integration rather than a typical agency engagement. I was inside the organisation, accountable for the quality and direction of the system alongside the teams already in place, not parachuted in from outside with a clean slate and no context.
My responsibilities covered creative direction, brand oversight, delivery management, and team leadership across the full lifecycle of the design system, from establishing foundations through to adoption across product teams.
The Core Challenge
Building a design system for a single product team is hard enough. Building one for a global organisation with multiple existing teams, entrenched ways of working, and a brand as tightly governed as BT's is a different thing entirely.
The technical challenge of creating a comprehensive, scalable component library with robust documentation was substantial. But the organisational challenge was just as significant, and arguably harder. Design systems only work if teams actually use them. That means the system has to be easy enough to adopt that it becomes the obvious choice, and authoritative enough that teams trust it over their own locally evolved patterns. Getting both right at the same time, across teams with different priorities and levels of design maturity, took as much change management as it did craft.
The Decisions That Mattered
The first decision was to audit before we built anything. The instinct on a project like this is to start creating, and there was pressure to do exactly that. I pushed back. Before a single component was designed, I had the team catalogue what existed across BT Global's digital estate, identifying inconsistencies and working out which locally evolved solutions were actually worth keeping. That groundwork meant the system absorbed the best of what was already there, rather than asking teams to abandon work they had invested in and trusted.
The second decision was that accessibility had to go in from the start, not the end. I set this as non-negotiable from day one, embedding WCAG standards into every component specification rather than treating compliance as a checklist to be applied at the finish line. Every colour token, type scale, interactive state, and focus behaviour was designed with accessibility as a first principle. Given BT's public-facing obligations this wasn't optional, but it also produced a more considered and robust system than a retrofitted approach would have.
The third decision was about documentation, and how seriously to take it. I've seen too many design systems fail, not because the components were wrong but because nobody could figure out how to use them. I made sure the team invested heavily in usage guidelines, best practice examples, and implementation support, written for both designers and developers in language that made the right choice the obvious one. The goal was a system teams could onboard to independently, without needing a workshop or a call with the core team every time they wanted to add a component.
Outcome
The BT Global Design System was adopted across multiple product teams and became the working reference for digital design across the global estate. Design-to-development time came down as teams moved from locally produced components to a shared library. Accessibility compliance improved consistently across products. And perhaps more tellingly, teams that had initially been sceptical of the system started contributing back to it. Which is usually the sign that it's actually working.