Lead Data Scientist

London, UK (Hybrid)

Salary Not AvailableSenior Level5+ years expFull time

Posted 2 months ago

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Job Summary

Own end-to-end ML platforms for behavioural modelling in a subscription context, blending production-grade pipelines with rapid experimentation and client-facing data delivery.

  • ML Infrastructure & Orchestration: build time-series pipelines from ingestion to deployment, with config-driven workflows and robust data quality checks.
  • MLOps & Governance: establish experiment tracking, model registry, drift/quality monitoring, and CI/CD collaboration for a small team.
  • Architecture & Customer Collaboration: partner with CTO and client teams to design scalable systems, multiple models, and forecast horizons that maximize predictive value.

Job Description

Responsibilities

  • Design and implement end-to-end ML pipelines from data ingestion through model deployment and signal delivery
  • Transform client-specific Jupyter notebooks into modular, config-driven pipelines using orchestration tools such as Prefect/Airflow
  • Build robust API connectors handling schema evolution, incremental updates, and data quality validation
  • Implement comprehensive machine learning model evaluation frameworks blending technical metrics (precision, recall, PRAUC, probability calibration) with business outcomes
  • Develop AutoML capabilities optimised for time-series behavioural data and subscription lifecycles
  • Implement sophisticated feature engineering for event-based data
  • Design multi-model systems handling various prediction horizons and conversion definitions
  • Optimise hyperparameter tuning using frameworks like Optuna, AutoGluon, or H2O
  • Establish MLOps practices appropriate for a small team: experiment tracking, model registry, and monitoring
  • Collaborate with engineering on CI/CD pipelines, testing frameworks, and deployment automation

Requirements

  • 5-8+ years building production ML systems with demonstrable business impact
  • Strong experience with time-series analysis and behavioural event modelling
  • Deep expertise in Python with high code quality standards
  • Experience with modern ML stack (e.g. pandas/polars, sklearn, xgboost, PyTorch/TensorFlow)
  • Proven track record delivering end-to-end ML pipelines: ingestion → feature engineering → training → deployment → monitoring
  • Hands-on experience with cloud data warehouses (e.g. BigQuery, Snowflake)
  • Track record of building automated, scalable systems from initial prototypes
  • Right to Work in the UK (we cannot sponsor visas)
  • Ability to work from Central London office 3 days/week (we believe in-person collaboration is crucial at this early stage)
  • You may be a great fit if you have any of the following...

Preferred

  • AutoML framework experience (e.g. AutoGluon, TPOT, Optuna, H2O.ai)
  • MLOps tooling (e.g. MLflow, Weights & Biases, Evidently)
  • Hands-on experience with orchestration tools (e.g. Prefect, Airflow, Dagster)
  • Building robust API/ETL connectors with retry logic and incremental loading
  • Statistical depth beyond standard metrics: calibration, cost-sensitive learning, causal inference
  • Passionate about leveraging the latest LLM tooling for accelerated AI-enhanced delivery without compromising on quality
  • Domain knowledge bonus points - Marketing attribution and conversion modelling, Mobile app analytics and user lifecycle prediction, Ad-tech ecosystem and privacy regulations (ATT, GDPR), Subscription business metrics and retention modelling

Benefits

  • Holidays: 25 days of annual paid leave, plus bank holidays.
  • Flexibility: 3 days/week in Central London office, remote otherwise
  • Equipment: Top-spec MacBook Pro and any tools you need
  • Learning Budget: Conferences, courses, and resources to stay current
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Day30

Day30 is a performance marketing consultancy specializing in consumer subscription apps. We help marketing teams navigate signal loss in the post-privacy era, enabling them to optimize campaigns for the metrics that truly matter—CAC, LTV, and Payback Period.Our mission is to make cutting-edge data science techniques accessible to performance marketers. We offer a range of services designed to empower in-house teams, from measurement and reporting audits to channel management—extending your team’s capabilities and driving smarter growth.

Founded in 2025
London, England, GBR
2 employees

Headcount Trend

Current headcount: ~3