I had lived and worked in the Bay Area for eight years before I moved back to London for family reasons. I ran two London loops in early 2024, both for senior backend roles, both at well-known UK-headquartered scale-ups. Both ended in offers. Both loops had differences from the US loops I knew that I had not been ready for. I want to write down the structural differences (which are easy to misread as cultural) and the cultural differences (which are easy to misread as structural). The names of the companies are anonymized; both are public-facing names you would recognize.
The structural differences
The loop shape was familiar. Five rounds. One coding, one system design, one behavioral, one hiring manager, one team-fit. What was different was wrapped around the loop.
Right to work vs visa
The first thing the recruiter asked, before any technical screen, was about my right to work in the UK. This is not because the company was hostile; it is because the cost structure of sponsoring a Skilled Worker visa in the UK is non-trivial (a sponsor licence, the certificate of sponsorship, the immigration skills charge, and the candidate's own visa fees and Immigration Health Surcharge). Most companies will sponsor for a senior engineer if the role merits it; many will not invest the recruiter's time into a loop until they know whether sponsorship is needed.
In my case I had a settled status from my prior UK time, so the right-to-work question was a one-line confirmation. If I had needed sponsorship, the call would have included an explicit "is sponsorship something you need" question and the recruiter would have looped in their internal mobility person before scheduling the technical screen. This is not a US-style assumed-citizenship-or-green-card setup. It is faster than the US H1B process for the candidate (decision in weeks, not months) but slower for the recruiter (the company has to invest before any signal).
Comp bands
The public discourse about "London comp is half of Bay Area comp" is partly true and partly an artifact of how comp is structured. For the same level (senior backend), my offers were:
The equivalent US senior offers I had been getting two years earlier were base 200k+ USD with much larger equity grants. The base alone is not the right comparison; cost of living, healthcare (NHS plus private through the employer in both my offers), pension contributions, and the equity treatment are all different. The total-comp gap was real but smaller than the base-comp gap suggests, and the buying-power gap was narrower than the total-comp gap. I want to flag this because the framing of "London comp is bad" is the framing that pushes candidates to negotiate poorly. The honest framing is that London comp is materially below US tech-hub comp at the senior level, but it is also less variable across companies and the negotiation room is narrower.
IR35 and contracting (this matters even for full-time roles)
IR35 is a UK tax rule that determines whether an off-payroll worker is being treated as a disguised employee. It applies to contractors, not to permanent employees, but it shapes the broader engineering market in two ways. First, the rate ceiling for senior contractors is lower than it was pre-2017, which has compressed contractor day rates and has made some senior engineers reconsider permanent roles. Second, the conversation about "what is your engagement structure" comes up earlier in UK loops than in US loops. Even in my permanent-role loops, the recruiter asked whether I was open to contract-to-permanent or fixed-term. In the US the same question would have been seen as unusual; in the UK it is normal because IR35 has reshaped what the labor market looks like.
I was applying for permanent roles. The IR35 conversation was brief in both loops. But I was glad I had read the basics (inside vs outside IR35, the responsibility shift to the engager) before the calls.
The cultural differences in the rounds
The rounds themselves were technically calibrated similarly to US loops. The cultural register was different.
The behavioral round was less explicit about dimensions
In US FAANG loops the behavioral round usually has a named rubric (drive, ownership, collaboration). Both London behavioral rounds I sat through were less explicit. The interviewer asked open-ended questions and was scoring me on dimensions I could feel but not always name. The danger here for someone coming from a US loop is to over-narrate the framework you are using. I caught myself in round 1 of loop A saying "this is going to be a STAR-shaped story" and the interviewer's face shifted slightly. He did not want to be told the structure; he wanted to listen to the story. I dropped the framing for the rest of the round.
The pushback in technical rounds was softer
In US loops the interviewer often pushes back hard on a design choice to test how you respond under pressure. In both London loops the pushback was gentler in tone but no less substantive. The substance was the same; the surface was different. The risk for me was reading the softer surface as agreement. In one round I took a soft pushback as a clarification rather than a disagreement, kept going, and only realized at the end that the interviewer had wanted me to revise my approach 10 minutes earlier. I got the offer but the round-level feedback flagged it.
"What questions do you have for us" carries more weight
US loops usually allocate the last 5 minutes to candidate questions; the questions are sometimes a tiebreaker but usually a formality. Both London loops weighted the questions section more heavily. In one round the interviewer told me afterward that the question I asked (about how the team handles disagreement on technical direction) had been the strongest signal of the round, because the answer required the team to have a real opinion about how they worked, and most candidates ask softer questions.
I now prepare candidate questions for any UK loop more carefully than I would for a US loop. The questions are part of the signal, not a footnote.
The two pieces of UK-specific homework I skipped
I took offer B and have been there 11 months. Two things I would do differently if I ran another UK loop tomorrow.
The first is the comp negotiation. I anchored on the original offer and got a small equity bump. In retrospect the equity-band flexibility was wider than I had assumed, and I could have pushed harder on the equity vesting cliff (offer B had a 1 year cliff; some peers I have since talked to negotiated that down to 6 months for senior hires). The single piece of information I should have had before the negotiation call was a clear question to ask about cliff length. I would have asked it.
The second is the cultural register on behavioral rounds. I would walk in next time with a UK-calibrated story bank, not a US-calibrated one. The US bank is heavy on "impact narratives" with the candidate as the hero of the story. The UK register prefers stories where the team is the hero and the candidate is a contributor with a specific role. The same story can be told either way; the cultural fit is in the framing. Telling a US-framed story in a UK round is one of those things that does not get you rejected but does keep you from being the strongest candidate in the loop.