I'm not up to date with the state of the art, but the March 2020 paper from the Bank of England seemed clear that balances would be held on a ledger at the Bank

I'm not up to date with the state of the art, but the March 2020 paper from the Bank of England seemed clear that balances would be held on a ledger at the Bank of England. Whether the balances on this ledger would be assigned to specific beneficiary owners, or only to intermediaries (like retail banks) wasn't clear. But, in either case, only the central bank could issue/mint new balances.