//I wonder if the boot was on the other foot, though, and we had not had the orders we were promised, despite maintaining exports, would we have been cross?//
They were not promised them. I've read the relevant parts of the AZ/EU contract and it made no promises and no contractual quantities or dates were itemised. It simply mentions "best efforts".
The reason the EU is short of vaccines is because, in its usual inimitable fashion, it prevaricated, argued over the price and overburdened the approval and purchase process with its ridiculous levels of bureaucracy. The worst thing EU nations did was to pass responsibility for procurement to the EU. Now, to put right their disastrous errors they are considering requisitioning or sequestrating goods made by a commercial company. They are not theirs to seize.
It's OK the behave the way they did when arguing over the supply of beetroot. It's not OK when health and lives are at stake. I have many friends on the Continent and they are tearing their hair out at the lunacy and ineptitude of it all. It should serve as a timely reminder to all of them that their interests are not best served by their nations' membership of the EU.