Staff Data Scientist - Network in London

Relay is fundamentally reshaping how goods move in an online era. Backed by Europe's largest‑ever logistics Series A ($35M), Relay is scaling faster than 99.98% of venture‑backed startups. We're assembling the most talent‑dense team the logistics industry has ever seen. Relay's Mission is to free commerce from friction. Today, high delivery costs act as a hidden tax on e-commerce, quietly shaping what can be sold online and limiting who can participate. We envision a world where more goods move more freely between more people, making the online shopping experience seamless and accessible to everyone.

About the role: Relay’s network runs on forecasts. Every shift released in sortation, every middle‑mile van dispatched, every last‑mile route planned, every expansion decision made - all downstream of models that predict how parcels move through our system. When those models are right, the network runs efficiently and cost per parcel drops. When they drift, the cost compounds across every stage of the operation. The Network squad builds and maintains the forecasting engine that powers all of it, and Demand Forecasting is its core: one forecast of what will be available to sort, at outcode granularity, from D0 out to D30.

As a Staff Data Scientist, you are the technical anchor for Demand Forecasting. You own the hardest and most ambiguous parts of the forecast, and you set the methodology and validation standards the rest of the area works to. That means owning the single integrated forecast of what volume the network will have to move, by area and out to thirty days, which the demand‑management layer then turns into the operational plan the sort centres and transport teams run on. It means owning the model‑driven end of that forecast, where the horizon runs past any live tracking data and expected parcels have to be generated from models rather than observed. It means owning the forecast of inbound international volume, one of the hardest prediction problems we have. And it means owning the models that predict each parcel's size and weight, which turn a parcel count into the physical volume that actually has to be sorted and loaded.

This is a hands‑on role. You will spend most of your time building, not managing. You set the direction for how Demand Forecasting models, evaluates and ships its work, and you raise the technical bar across the area, but you do it as the most senior individual contributor in the room, on the tools. You'll work alongside a Senior Data Scientist who owns the domestic volume forecasts, an ML Engineer who keeps the models running reliably in production, and an Analyst who owns forecast accuracy and data quality. People leadership, strategy and cross‑squad priorities sit with the Data Science Manager who leads the squad; you own the science.

What You’ll Do:

• Own the integrated forecast end to end. Blend live tracking signals in the near term with model-generated parcels further out into a single view, by area, from today to thirty days ahead.
• Build the hardest models in the area. The model‑generated long‑horizon forecast, the inbound‑international volume forecast, and the parcel size and weight models.
• Set the methodology and validation standards for Demand Forecasting.
• Raise the technical bar. Review approaches, make the model-choice and build‑vs‑buy calls, and mentor the Senior Data Scientist and Analyst.
• Define the forecast's interfaces.
• Learn the operational processes your models serve.
• Own production quality across the estate.
• Work with Finance to keep the handoff between operational and financial models reliable.
• Quantify the impact of model error on cost per parcel.

Who Will Thrive in This Role?

• You have been the technical anchor on a modelling team before.
• You think in interconnected systems.
• A deep track record of building and delivering models from ambiguous starting points.
• Strong Python and SQL skills.
• At least 8 years in a data science or quantitative modelling role.
• You communicate with non-technical stakeholders with authority.
• You're comfortable using AI tools to accelerate your workflow.
• This role suits someone who wants to see whether their models made a real difference to how the network operates.
• Logistics or delivery network experience is a plus.

Compensation, Benefits & Workplace:

• Generous equity, richer than 99% of European startups.
• Private health & dental coverage.
• 25 days of holidays.
• Located in Shoreditch, our office set-up enables in‑person interactions.
• Hardware of your choice.
• Extensive perks.

Who Thrives at Relay?

• Aim with Precision.
• Play to Win.
• 1% Better Every Day.
• All In, All the Time.
• People-Powered Greatness.
• Grow the Whole Pie.

Relay is an equal‑opportunity employer committed to diversity, inclusion, and fostering a workplace where everyone thrives.