The Evening Standard reports ministers from both countries have been "liaising" on the development of the new technology, which is expected to be ready within two or three weeks.
But why are the two allies collaborating on building their own 'surveillance' app instead of adopting a model proposed by Apple or Google? Well, apparently, British officials felt Apple's treatment of user privacy was "too cautious".
The app will use bluetooth to collect data from the phones of everybody one passes; should one of them test positive, a user will be notified.
A consultant to the French government said: "Apple appeared to be much more cautious about protecting client data and privacy than the French or British authorities."To be sure, Matthew Gould, head of the unit at the NHS that's in charge of developing the app, has said the location-tracking feature - pretty much the only reason to use the app - would be "opt-in".
The smartphone app will track and trace any possibly affected persons near the user. Some have feared its use of Bluetooth could divulge confidential information about people's locations.
Matthew Gould, head of the NHS unit developing the app, has said the location aspect of the system would be "an opt in" and not compulsory.We can't help but wonder: Why is HMG pouring so much time and money into developing an app that many members of the public might be uncomfortable with use?
"If you want to protect the NHS and stop it being overwhelmed while at the same time want to get the economy moving, the app is going to be part of the essential strategy," he told the Commons science and technology committee.
But Bruno Macaes, a diplomat and expert on the politics of cyber operations, thinks that both the British and French tracer apps may be underpowered.
He believes they will need at least 60 per cent participation by the population, induced by either cash payments or dropping phone charges, or making it compulsory by law.
Which raises questions about its efficacy, since health officials fear that fewer than half of Britons will willingly download the act given the potential risks to privacy.
Just something to think about.