Case studies

A Deep Dive into DHSC's Track & Trace App Technical Policy for Safeguarding UK Citizens

key fact

The aim of the NHS Test and Trace (T&T) programme is to break the chains of Covid-19 transmission to enable society to return to a more normal way of life.


In Spring 2020 saw the UK immersed in a complex and challenging situation. The population was locked down, hospitals were extremely busy, and COVID infections were increasing.    

In April, the Department of Health and Social Care (DHSC) was tasked with the rapid roll-out of a new NHS COVID-19 contact tracing app to support the wider Test and Trace (T&T) initiative. This major technology programme was defined by speed, complexity, innovation, agility, and continuous improvement. The App was a key part of the national strategy towards managing the pandemic and limiting future infections

The Alan Turing Institute and Zuhlke Engineering led the design and build of technology that was ground-breaking in its technical complexity. Mason Advisory played a crucial role in translating the strategy behind the App into reality. 

Within an Agile framework, government policy decisions had to be informed, taken, and integrated into the build, fast. This demanded extensive leadership consultation across science, technology, mobile platforms, healthcare, industry, regulatory bodies, ministerial departments and ministers themselves.  


The DHSC was already heavily committed to dealing with many urgent priorities. So, extra resource was needed on this programme. Mason Advisory identified four consultants, offering over 120 years’ senior experience in technology transformation, strategy, and rollout. Within days, the team joined DHSC’s special policy team of senior civil servants. 

The highly scalable app was pioneering in using Google Apple Exposure Notification (GAEN) API Mode 2 (never before used for a contact tracing App) and complex, interdependent calculations. It deployed Bluetooth Low Energy (BLE) to understand contact distance and exposure time, applying complex risk algorithms and thresholds to identify possible risk and determine self-isolation notifications. These thresholds had to consider multiple inter-related scenarios, including uptake, age-appropriate use, privacy, workplace scenarios and cross border compatibility. 

Our team applied their expertise to facilitate important decisions at record speed, so that the App’s development was unimpeded. They negotiated the first ever zero rating of such an App with mobile platforms, ensuring that the public would not be charged for using it. They applied deep industry knowledge to secure appropriate pausing parameters, facilitating post-lockdown opening of business outlets. They deployed technical and security expertise to ensure the app was compatible with others across UK devolved and crown territories. Across all stakeholders, they forged relationships and negotiations to secure policy decisions that were rapidly fed back into the App – even where no precedent existed. It was “perhaps the first time that policy has been built into the Agile development lifecycle”, according to Zuhlke. 

Mason Advisory also managed the response to institutional and public interest, including a communications campaign and transparent publication of the App’s source code, related DPIA and FAQs.  


To achieve its critical role in breaking transmission, the App had to achieve maximum uptake from day one. It was launched nationally in September 2020 – four months after Mason Advisory came on board. It has been downloaded by over 31 million users, has alerted 17.3 million users to exposure risk, and is estimated to have prevented over 600,000 COVID infections since launch. The programme has set a new blueprint for policy integration into an Agile project. It demonstrates the ability to rapidly integrate policy and technology to respond effectively to public health crises in the future. 

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