A pilot deployment began in May 2020, but on 18 June development of the app was abandoned in favour of a second design using the Apple/Google Exposure Notification system.

[17] In March 2020, NHSX commissioned a contact tracing app to monitor the spread in the United Kingdom of the coronavirus disease 2019 (COVID-19) in the 2020 pandemic,[18] developed by the Pivotal division of American software company VMware.

[27] Replying to a question at the government's daily briefing on 8 June, Hancock was unable to give a date for rollout of the app in England, saying it would be brought in "when it's right to do so".

[28] On 17 June, Lord Bethell, junior minister for Innovation at the Department of Health and Social Care, said "we're seeking to get something going before the winter ... it isn't a priority for us at the moment".

[29] On 18 June, Health Secretary Matt Hancock announced development would switch to the Apple/Google system after admitting that Apple's restrictions on usage of Bluetooth prevented the app from working effectively.

[35][36] Over 150 of the UK's security and privacy experts warned the app's data could be used by 'a bad actor (state, private sector, or hacker)' to spy on citizens.

[33][37] Fears were discussed by the House of Commons' Human Rights Select Committee about plans for the app to record user location data.

[citation needed] The second version of the app, released nationwide, addressed these concerns by employing a decentralised framework, the Apple/Google Exposure Notification system.

[45][46] Testing of the app by NHS volunteer responders, and selected residents of the Isle of Wight and the London Borough of Newham, began around 13 August.

[55] After approximately two weeks the app had been downloaded around 16 million times, and Sky News reported that only one alert for an outbreak linked to a venue had been sent.

It was concluded that during the first months of the second wave of the COVID-19 pandemic, the 1.7 million exposure notifications sent by the app prevented around 600,000 cases of infection in England and Wales between its launch on 24 September 2020 and the end of December 2020.

This issue was addressed quickly, and from 27 September users could request a code from NHS Test and Trace which they could use to log a positive result.

[63] It was reported that preparations for the update to the app in late October uncovered a configuration error in the initial version: the threshold for the time spent near an infectious person had been too high, leading to fewer alerts to users.

[13] Privacy safeguards meant that people notified by the app to self-isolate could not claim the £500 Test and Trace Support Payment under the scheme which began on 28 September 2020.

[67] In late July, the government responded by expanding the list of critical occupations, adding sectors including waste disposal, the food industry and transport.

[68] Further changes were made on 16 August: contacts of infected people no longer have to isolate if they are under the age of 18 or if they had their second vaccine dose at least 14 days previously.

[73][21] Around 17 June, Gould and Lewis returned to their other duties, and Simon Thompson – chief product officer at online supermarket Ocado and a former Apple executive – was brought in to manage the project.