Case Study
Designing the next-generation Counter Terminal POS to replace Post Office's legacy Horizon platform — covering Cash Drawer Association, Closed Basket Reversals, and Pouch Acceptance across a network of 11,500 branches.
I was embedded as UX/Product Designer on the Counter Terminal programme, responsible for designing feature flows across the next-generation POS system replacing Post Office's legacy Horizon platform.
My work centred on building detailed user scenarios to address the diverse needs of postmasters, clerks, and customers — collaborating with stakeholders to understand pain points and operational workflows, and crafting flows that balanced usability, efficiency, and accessibility within a highly constrained enterprise environment.
I worked within a cross-functional team across three feature deliveries. Engineering confirmed which system states the CTA and BOA applications could actually report, and validated technical feasibility of each design option. Content design reviewed and refined all in-product messaging for tone and clarity.
Product management prioritised which scenarios shipped first, using real support-call volume to sequence the work — ensuring the most-impactful error states were addressed earliest.
A Discover–Define–Design–Deliver framework, applied consistently across all three Counter Terminal features.
Reviewed scoped requirements with engineering to understand exactly how the CTA and BOA applications could each independently drift out of sync — cataloguing every possible state combination before any design work began.
Turned each system state into a Jira user story with Given/When/Then acceptance criteria, agreed with engineering. Defined one shared goal per feature: every mismatch or error surfaces a clear message and a concrete next action.
Designed two options per scenario in Figma, testing the same message and action pattern against different real surrounding basket and navigation states. Copy was reviewed and refined with content design for tone and clarity.
Specified the exact trigger, message, and action for every scenario in a format engineering could build directly from. Prioritisation was sequenced against real support-call volume to maximise early impact.
Three choices that shaped how every feature was designed and delivered.
Two distinct design directions were explored for every scenario before any direction was chosen — giving stakeholders a genuine decision rather than a rubber-stamp, and forcing sharper thinking about trade-offs between UI complexity and postmaster comprehension.
Scenarios weren't prioritised by design complexity — they were sequenced by actual support-call volume. The highest-frequency failure states shipped first. This kept the work grounded in operational impact rather than design preference or build convenience.
No error state was considered complete unless it surfaced a clear message and a concrete next action. The consistent principle across all three features: a postmaster should never be left wondering what to do next — every dead end became a decision point.
Four workstreams, each presented as a standalone case study deck. These cover Cash Drawer Association, Refund on Failed Transaction, Pouch Acceptance, and Closed Basket Reversals — sequenced in the order they were designed and delivered.
What made this environment genuinely complex to design for.
CTA and BOA are separate applications that each hold partial views of the same transaction. Designing for states that existed in one system but were invisible to the other required close engineering collaboration to map exactly what each application could and couldn't surface — before a single screen could be designed.
The Counter Terminal had no mature component library at the start of the engagement. Each feature was designed within an emerging system — balancing internal consistency with delivery speed, and in doing so, contributing to system-level patterns that didn't yet exist.
The 11,500-branch network spans high-street franchise managers and sole traders in rural communities. Designs had to work across highly variable digital literacy levels — with no assumption of familiarity beyond the core terminal workflow, and clear guidance at every step for both postmasters and counter clerks.
Three parallel workstreams meant some lower-frequency edge cases were deferred to later sprints. Every de-scoping decision was made explicitly — prioritised against real support-call volume, agreed with product and engineering, and documented — rather than quietly dropped.
"I am really pleased with his designs for our project. He has smashed it with understanding and creating the flows of each story fully. Really excellent work — this has come together really nicely now after we were a bit start/stop with previous UX folks. Johnny is an asset to the Counter Terminal team and a really lovely guy to work with!"
"I just wanted to give Johnny and his UI/UX team mate a massive shout out for all their help with the 'Transaction Recovery' process. Both have been a massive help in forming this proposition."
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Senior product design available for engagements across enterprise ecommerce, fintech, and regulated systems.
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