> The UK's coronavirus contact-tracing app is set to use a different model to the one proposed by Apple and Google, despite concerns raised about privacy and performance.
> The NHS says it has a way to make the software work "sufficiently well" on iPhones without users having to keep it active and on-screen.
> That limitation has posed problems for similar apps in other countries.
> Experts from GCHQ's National Cyber Security Centre have aided the effort.
At the time, I definitely saw people assuming that this meant that some kind of exploit was being used to achieve access to Bluetooth while the app was inactive, even though regular APIs do not permit this. The new technical information doesn't directly address this point, though the Register article does suggest a plausible alternative, whereby one user with an actively-running app can cause the app to wake on other users' phones by sending out a Bluetooth LE broadcast. I've no idea how this would perform in practice.