TL;DR: Jonny Williams, who advises UK public sector clients on digital strategy for Red Hat, says the sovereignty test ought to be how much command Whitehall keeps over the systems it depends on — not the passport of the company that built them. His intervention arrives while MPs press ministers for a workable plan on sovereign capability.

Williams poses it as an operational question. Sovereignty, in his account, is a matter of agency, of choice, of control, and geography barely enters into it. Tolerable dependency comes down to whether a department can operate, inspect and repair what it runs without a vendor first granting leave — and to who actually owns the technology. Public bodies, he argues, need a clear-eyed inventory: what they lean on, on what terms, and for how many years.

That framing cuts against the instinct provoked by the Science, Innovation and Technology Committee’s July report. MPs warned that without a credible route to sovereign capability — in space and quantum as much as AI — Britain risks having access severed at an ally’s discretion, pointing to recent US curbs on certain models as proof the exposure is real. The committee also found that government lacks any coherent strategic framework for turning UK scientific strength into economic and diplomatic advantage. Dame Chi Onwurah, its chair, has said a strategy must spell out what counts as an acceptable degree of reliance, and that trusting to Britain’s international leverage may not be enough on its own.

Enterprise open source is Williams’s proposed answer. Standardising on it leaves the source in public hands even when a supplier rewrites its terms or restricts what customers can reach, he said, and the argument holds all the way down the stack — the model layer, then the operating system and the cloud beneath it. Visibility into the code, and the freedom to change it or move elsewhere, follow from the licence rather than from the vendor’s goodwill.

The disagreement is commercial as much as philosophical. Define sovereignty geographically and procurement tilts towards British-owned suppliers and domestic data centres. Define it as control and the criteria become licensing terms, exit rights and auditability — a bar plenty of overseas vendors already clear, and some UK ones do not.

Looking forward: Ministers are separately weighing what the withdrawal of frontier model access would cost the economy and national security, work Resultsense covered earlier this week. The definitional argument will sharpen as that assessment lands, because the answer decides whether “sovereign” functions as a procurement filter or an architectural requirement — and which suppliers the £500m Sovereign AI Fund can back.