---
title: 'Principal Data Scientist at marshmallow'
canonical: 'https://feeny.ai/job/principal-data-scientist-marshmallow-london-s5yzrs5hcnwz'
type: 'job'
last_seen: '2026-09-12'
---

# Principal Data Scientist at marshmallow

- **Company:** marshmallow
- **Location:** London, United Kingdom
- **Employment:** full-time
- **Work type:** hybrid
- **Posted:** 2026-09-09
- **Last confirmed live:** 2026-09-12
- **Apply:** https://jobs.ashbyhq.com/marshmallow/9c4c710f-6e8a-4081-84ad-325d58832e3b

## Job description

We’re on a mission to make migration easy.

We started building Marshmallow in 2017. Since then, we’ve grown from 3 to 700+ people, gained unicorn status, raised ~£140M over three funding rounds, turned profitable, insured millions of drivers and lent millions in car loans.

But we’re only just getting started. Our goal is to become one of the largest financial services providers in the world. Over the next 10 years we’ll grow exponentially, not only by scaling our existing products, but also by building new ones.

To achieve our goals we need incredibly ambitious, commercially driven people who never settle for ‘good enough’. Marshmallowers are hungry for autonomy and ownership, and would rather improve than coast. Everyone raises standards and has an impact, with a focus on collective success over self-interest.

We’ve created an environment where curious, tenacious people win and grow together. If that sounds motivating, this could be the place for you.

London (hybrid, 3 days in office)

Data Science at Marshmallow Our Data Science team partners across the business to turn data into better decisions, smarter products, and simpler customer journeys. We work closely with Product, Engineering, and Operations to build and ship models and AI systems that are reliable in production and deliver measurable impact. Within Data Science, this role sits in Claims, supporting the function and the broader ambition to automate more of the claims journey. Claims is one of Marshmallow's most important customer touchpoints, and we're looking for a Principal Data Scientist who can provide technical leadership across traditional ML and Generative AI, bring system-level thinking to how we scale decisioning, and confidently challenge proposals to ensure we build robust, sustainable solutions.

## What you'll be doing

- Provide technical leadership for data science across Claims Fraud, shaping the approach to risk decisioning and fraud detection in partnership with Product and Engineering
- Design, build and iterate on production ML and Generative AI/LLM systems that support claims validation and automation
- Collaborate closely with other Claims data scientists to bring system-level thinking to how models, data and workflows fit together, identifying architectural improvements needed to scale decisioning and reduce time-to-production
- Be vocal about the platform and tooling investments needed (monitoring, feedback loops, QA) to achieve AI-driven end to end claims automation
- Advocate for robust, scalable, and strategically aligned technical solutions in cross-functional discussions, ensuring current systems and infrastructure contribute to the multi-year vision for automated claims handling
- Set a high bar for statistical rigour, experimentation and measurement, helping improve how Claims performance and uncertainty are understood and communicated to senior stakeholders

## Who You Are

- You think in systems: you can connect the dots between data science, engineering, and product to shape scalable solutions that build on each other over time.
- You're confident in challenging assumptions and pushing for the right approach, using strong communication skills to influence stakeholders across seniority levels and disciplines with clear, pragmatic reasoning.
- You thrive in ambiguity and change, staying resilient and effective during transitions while bringing structure, clarity, and momentum to complex problem spaces.
- You're motivated by real-world impact, partnering closely with cross-functional teams to drive meaningful automation and better customer outcomes across the claims journey.

## What You'll Bring

- Significant commercial experience delivering end-to-end Machine Learning solutions, from problem framing and experimentation through to production deployment and ongoing monitoring
- Hands-on experience building and shipping Generative AI systems in production (not just prototypes), including evaluation, safety/quality considerations, and integration into customer or operational workflows
- Strong statistical and modelling foundation, with experience in risk-based decisioning under uncertainty (e.g., fraud, credit, insurance, or other regulated domains)
- Proven ability to influence technical direction across Data Science and Engineering, including shaping scalable model/service integration patterns and challenging proposals to drive robust, long-term solutions
- Strong stakeholder management skills, with confidence communicating trade-offs and pushing back constructively with Product and Engineering to ensure high-quality outcomes

## Perks of the job

- Bonus scheme designed to reward high performance
- Private medical insurance with Vitality, mental health support with Oliva
- Personal learning budget and 2 dedicated L&D days a year
- Monthly flexible benefits budget to spend as you choose
- 25 days holiday plus bank holidays
- 4 weeks Work From Anywhere per year

We are able to offer visa sponsorship for this position.

Our process

- Initial call with a member from our Talent Team (30 mins)
- Past Experience interview with Hiring Manager (60 mins)
- Systems Design & Technical interview with a couple of the team (90 mins)
- Culture interview (60 mins)

Diversity of thought We know the best ideas come from having different perspectives in the room - and we're committed to hiring fairly, regardless of background, identity or experience. If you see yourself in this role, we'd encourage you to apply.

## About marshmallow

## Company Overview
- **One-liner**: Marshmallow is a fintech company that uses proprietary technology to offer fairer car insurance and other financial services to newcomers in the UK.
- **Entity Type**: Private (Series C, Unicorn status)
- **Headquarters**: London, England, United Kingdom
- **Founded**: 2017
- **Founders**: Alexander Kent-Braham and Oliver Kent-Braham

## Core Business
- **Primary industry/industries**: Fintech, Insurance (Car, Home), Consumer Finance
- **Target customers**: B2C – primarily newcomers to the UK who are underserved by traditional insurers
- **Mission or purpose statement**: "To make migration easy" by providing fair access to financial services for people who move countries.

## Products & Services
- **Car Insurance**: A data-driven car insurance product that prices based on a driver's global history, not just UK experience, offering fairer rates to newcomers. (Service)
- **Home Insurance**: An extension of their insurance offering, providing coverage for renters and homeowners. (Service)
- **Car Finance**: A lending product for car purchases, expanding their financial services ecosystem. (Service)

## Market Standing
- **Valuation/Market Cap**: Unicorn status (valuation over $1B) as of 2021; latest Series C in April 2025 at a valuation not publicly disclosed.
- **Key Metric**: Total funding of ~$228.8M (USD) across 8 rounds. Annual revenue estimated at $28.8M (USD).
- **Notable Investors/Partners**: Portage Ventures (lead, Series C), Passion Capital, Investec, SCOR, BlackRock, Columbia Lake Partners, Triple Point Ventures.
- **Growth Signals**: Turned profitable; doubled profit since 2023; 27% employee growth in 12 months; 50% female employees; expanded from car insurance into home insurance and car finance; 700+ employees; operates in 19 countries.

## Competitive Advantages
- **Proprietary Data & Pricing Models**: Uses its own technology to price risk based on a driver's global history, not just UK data, allowing it to serve a large, underserved market of newcomers that traditional insurers ignore or overcharge.
- **Mission-Driven Niche**: Focused exclusively on making migration easier, creating a strong brand and customer loyalty among a specific, growing demographic.
- **Full-Stack Fintech**: Has built its own technology stack from the ground up, giving it control over pricing, fraud detection, and customer experience, and enabling rapid expansion into new products (home insurance, car finance).

## Strategic Focus
- **Product Expansion**: Scaling beyond car insurance into home insurance and car finance, with a long-term goal of becoming a leading global financial services provider for migrants.
- **Geographic Growth**: Expanding its customer base and operational footprint, with offices in London and Budapest and employees across 19 countries.
- **Technology & Data**: Continuing to invest in proprietary data science and pricing models to maintain its competitive edge and enter new markets.

## Why Work Here
- **Culture & Values**: Described as low-ego, high-performance, and collaborative. Values include "autonomy and ownership," "relentless improvement," and "maximising impact, fast." Emphasis on collective success over self-interest.
- **Growth & Impact**: A fast-paced, high-growth environment (unicorn status, profitable, 27% employee growth in 12 months) with opportunities for significant ownership and career acceleration.
- **Flexible Working**: Flexible working policy; offices in London (The Featherstone Building, 66 City Road) and Budapest designed for collaboration.
- **Benefits**: Private healthcare (Vitality), mental health support (Oliva), cycle-to-work scheme, competitive bonus scheme, flexible benefits budget (Ben Mastercard), learning & training budgets, company socials, and 2 personal development days per year.
- **Engineering Culture**: Described as low-ego, high-performance, and collaborative. Teams have autonomy and ownership over their roadmaps. Focus on data science and proprietary tech.

## Sources
1. [marshmallow.com](https://www.marshmallow.com/jobs)
2. [marshmallow.com](https://www.marshmallow.com/our-story)
3. [linkedin.com](https://uk.linkedin.com/company/marshmallowltd)
4. [cbinsights.com](https://www.cbinsights.com/company/marshmallow-financial-services)
5. [otta.com](https://app.otta.com/companies/Marshmallow)

## Other roles at marshmallow

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