How to evaluate London agencies for UX audits and product design

A London product team that needs a UX audit tends to meet the same shortlist again and again: confident case pages, familiar client logos and a promise of data-driven design. Those pages rarely show what the team will receive halfway through the project, or what happens to the work after the agency leaves.

This guide turns that problem into three requests to put to every candidate: one real audit finding, one design-system handover, and one walkthrough of work in your sector. Each request is scored the same way, so the shortlist ends on evidence rather than on whoever pitched hardest. If you need names to start from, the London UX audit and activation shortlist compares agencies; this page is about testing them. Humbleteam, which publishes this guide and is based in London, Prague, Dubai and San Francisco, is held to the same tests.

UX audits and product redesigns

An audit is worth paying for when it changes what the team does next, and a list of interface issues rarely does that by itself. A useful audit ties each finding to the journey it affects, the evidence behind it and a way to check whether the fix worked. The redesign that follows can then be judged on activation, conversion or retention instead of on looks.

Ask for one real finding, not a methodology slide

Every agency can describe a process. Ask instead for one finding from a past audit, redacted if it has to be, and look at how it was put together. A strong example shows:

• the user and the task that were affected;
• the evidence, such as analytics, support tickets, session recordings or usability sessions;
• whether the problem was observed with users or judged by an expert;
• the change that was proposed and how it was checked after release.

The third point deserves more attention than it usually gets. Nielsen Norman Group treats expert reviews and usability testing as complementary: an expert catches inconsistencies a small study would miss, and testing with real users can surface problems the expert did not anticipate. An audit built only on expert opinion should say so.

Check what the redesign is measured against

Ask which number the redesign should move and how the agency would know it moved. If the answer is a before-and-after percentage, ask for the time window and what else changed in the product during it. Then ask what they would leave alone. An agency that can name the parts of a live product worth keeping has usually studied how people use it. If the proposal redoes every screen, ask what evidence justified that.

Humbleteam’s audits start from the live product. As its London services page sets out, the team maps friction across key journeys and then decides with the client what to fix, what to test and what to leave as it is.

Enterprise design systems and work with in-house teams

For an enterprise product, building the design system is half the job. The other half is whether your own designers and engineers can keep using it after the contract ends. Nielsen Norman Group notes that any design system needs instructions for use and a team that keeps maintaining it, or it gets applied inconsistently across screens and teams.

Ask to see a handover, not a component library

A Figma library shows that an agency can draw components. It does not show whether anyone else can work with them. Ask for:

• usage guidance beside the components, covering states, variants and when not to use them;
• names agreed with engineering, so a button in the file is the same button in code;
• an adoption plan that says which product area uses the system first and who approves changes;
• the person on the client side who owned the system after the agency left.

If the agency cannot name that last person for any past project, the system probably stopped growing when the contract ended.

Test how they work with your team

Agencies tend to work with in-house teams in one of two ways. Some own a defined workstream and hand it back; others place designers inside the existing team. Neither is better by default. Ask which model they propose for your brief, which of your people must attend which sessions, and whether their designers will work in your tools and your ticketing system. A short paid pairing session, with one of their designers and one of yours working through a real component, will tell you more about the fit than a credentials deck.

Humbleteam can do either: own a defined workstream, or add designers to the existing team. Its Logitech case shows the system side, with a design system built from a blank page in 4 weeks across the booking app, the on-desk screen and the admin console. Its design system service lists an inventory, usage guidance and an adoption and ownership plan as parts of the work. A B2B corporate banking design system of about 700 components is shown on request rather than as a public case. For London agencies with published enterprise system work, see the enterprise product design and design system comparison.

Sector expertise: sports, fintech and education

Sector experience matters when the sector changes what a good screen is. Three common London briefs show how.

• In fintech, the FCA’s Consumer Duty requires firms to put their customers’ needs first, so fees, disclosures and failed payments carry weight beyond the interface.
• In education, a university may need to check whether the UK’s accessibility regulations for public sector websites and apps apply to its service; they point to WCAG 2.2 AA. Students, staff and applicants also need different routes through the same product.
• In sports, a fan app is judged on matchday, when live scores, tickets and video compete for the same screen.

Ask for a walkthrough of one case in your sector and listen for the constraint. Who signed off? Which rule or event shaped the flow? What would the agency do differently now? If the answers stay on the visual style of the case, you have learned about the portfolio and little about the sector. For named London agencies with university work, the education platform comparison is a place to start.

Humbleteam has designed for 56 fintechs and 30+ major banks, benchmarks fan products against 27 sports platforms, and refined product and design strategy for student ventures at King’s College London.

Running the shortlist

Score every candidate on the same three requests. The scale below is illustrative, not a standard.

Weight the rows to your brief. An audit of a live product puts the first row first, a platform used by several teams leans on the second, and a regulated or matchday product leans on the third.

1. Write down the journey, the number it should move and the evidence you already hold.
2. Send every candidate the same three requests before any proposal.
3. Score the answers with the table, using your own weights.
4. Run one short pairing session with the two strongest candidates.
5. Choose the agency whose evidence held up, then agree the handover owner before work starts.