https://www.theguardian.com/world/2020/apr/13/nhs-coronavirus-app-memo-discussed-giving-ministers-power-to-de-anonymise-users

Exclusive: draft plans for contact-tracing app said device IDs could be used to identify users

A draft government memo explaining how the NHS contact-tracing app could stem the spread of the coronavirus said ministers might be given the ability to order “de-anonymisation” to identify people from their smartphones, the Guardian can reveal.