NHS – Owning the tech stack

Taking over from another IT supplier is always tricky and fraught with dangers.  How did Zaltek Digital go about owning the tech stack of a complex and well established public web service ?

The Challenge

The NHS Specialist Pharmacy Service (SPS) is an England wide service commissioned by NHS England.  It specialises in the implementation of system wide Medicines Optimisation activities led by the office of the Chief Pharmaceutical Officer for England. SPS’s users are primarily healthcare professionals working with medicines in the NHS.

As the new strategic digital partner for the NHS Specialist Pharmacy Service the first challenge was to take the reins from the incumbent supplier.  Getting control and owning the tech stack is critical.  Additionally, with the incumbent supplier leaving, lots of knowledge was leaving the building.  The SPS is a critical piece of NHS’s infrastructure with up to half-a-million 28-day active users for sustained periods.

SPS is a complex platform, optimised for high volume traffic with lots of technologies in play: WordPress, Elastic, Kubernetes, Kafka, Java, Javascript, React and lots more.  The SPS platform would put our developer and backend skills to the test!

The service was in the middle of being migrated from Amazon Web Services over to Google Cloud Platform and we needed to finish the job.

Our Approach

  • Understanding the tech stack through spikes.
  • Creating sandboxes (safe places) where we can make changes without risking the live system.
  • Taking control of the tech stack.
  • Understanding what each bit of technology does.
  • Create mitigations for the bits that we don’t have control over.
  • Lots of technical deep dives.
  • Continually replay our understanding back to the stakeholders via Show and Tells.
  • Creating an internal knowledge base.


What was critical is that we got into a position that we can recover if any part of the stack falls over. We focused on engaging with the stake holders explaining the architecture allowing them to take ownership and make informed decisions.

screenshot of sps website

screenshot of sps website

Zaltek took ownership of the tech stack!

Migration to Google Cloud was completed with no loss of service, furthermore we can confidently support the live running of the service. We’ve made improvements and fixed various issues.

“Thanks to all the hard work from the team.  We’ve covered lots of ground and are in a good solid position for the next phase of delivery” – Mark Middleton MD