In 2022, the UK took an ambitious step: founding the Government Digital Sustainability Alliance (GDSA), a cross-departmental body built to drive coordinated sustainability action across the entire UK government and its one million civil servants. In this session, two of the architects of this national effort will share what they've learned — the structural hurdles of cross-departmental coordination, the strategies that have moved stakeholders from indifference to action, and how AI sustainability has emerged as a key point of entry. We'll review the newly finalized UK Government Digital Sustainability Strategy and discuss its goals, implementation, and anticipated outcomes for constituents, including tech vendors.  We'll conclude with the latest emerging sustainability guidance for the AI systems lifecycle and the influence of national AI sovereignty goals.