Contractually, the UK have 80% minimum of all AZ production tied to the UK plants.
This actually meant that in December, we only had 4m doses instead of 30m by that time because of issues with UK facilities.
So in hindsight, the UK nailed it, the EU er... didn't. But - and it's a big but - I don't think they nailed it because of contractual wording. If the UK sites had repeated issues, we'd have been up poop creek without a paddle, as we'd have no recourse to the EU facility productions. So that part is luck, and why a "best efforts" clause is a no-brainer with the deal.
No, the reason we nailed it was due to the speed of the acquisition program. Critically, the order was three months earlier, so we had time to sort everything, work out niggles, get ahead of the pack.