Merck was the Oxford team's first choice of manufacturer. But the UK health minister overruled and told them they needed to use a British manufacturer. [1]

"[T]he Oxford-AstraZeneca vaccine was very nearly the Oxford-Merck vaccine - and under the terms of the agreement with the American pharmaceutical giant, there were no guarantees of supply.

The episode played out against the backdrop of the first phase of the pandemic. During March and April 2020, the University of Oxford negotiated a deal which would allow Merck to manufacture and distribute the vaccine it was in the process of developing.

The arrangement made sense. Unlike British-Swedish AstraZeneca, Merck had experience in making vaccines. Its senior executives had links to Oxford scientist and government adviser Sir John Bell.

Yet when the contract reached Matt Hancock's desk, the former adviser said, the health secretary refused to approve it, because it didn't include provisions specifically committing to supply the UK first."

[1] https://news.sky.com/story/covid-19-rejected-contracts-and-a...