Lewin Appleton-Fox

Data Engineering • MLOps • DevOps • Python • R

📧 lewin.a.f@gmail.com | 🌐 github.com/lewinfox

Profile

I'm a senior data engineer specialising in MLOps and DevOps. I've worked in both managerial and IC roles and have a strong track record in product development. I'm proficient at gathering requirements, collaborating with stakeholders, and managing expectations to deliver successful projects. I value a supportive and collaborative working environment and am always keen to learn from and teach others.

Technical Skills Highlights

Most of my work for the last five years has been with modern cloud-native data platforms in AWS and Azure. Typical tech stack: Python / dbt / Terraform / AWS / Docker.

Skill	Years Exp.	Notable Competencies / Specialisms
Linux	16	System configuration, CLI, bash scripting
Python	6	ETL, machine learning, CLI/GUI development
Cloud / IaC	5	Terraform, EC2, S3, Lambda, MWAA, Athena, RDS, ECS, cloud-native architecture
Docker	4	Containerisation, docker-compose, VSCode devcontainers, microservices
CI/CD	6	GitHub Actions (tests, docs, dbt deployments, websites)
Machine Learning	3	Propensity modelling, segmentation, tree-based models
LLMs	1	RAG, prompt engineering, Ollama, vector databases
MLOps	1	Containerisation, model serving, CI/CD for ML, MLFlow, model versioning
R	7	Shiny, tidyverse, package development, ML, CRAN package maintainer
dbt	4	Extensive use including custom Jinja macros
Snowflake	4	Sysadmin, UDFs, Snowpark

Open Source

Programming is a hobby as well as a job, and I'm passionate about open source software. I've contributed to a number of open source projects and maintain the following:

levitate - Fuzzy string comparison and similarity scoring.
icecream - User-friendly print debugging in R.
foodwebr - Draws function dependency graphs.

Engagements

Data Engineer | needles.io | Remote

Aug 2024 - Present

Providing data engineering services to a large NZ-based financial services firm.
Designed, built and maintained enterprise-scale ETL systems in AWS (Athena, RDS, S3, Airflow/MWAA, dbt, Python, Terraform).
Designed data warehouse architecture and data flows supporting multiple business teams.
Improved local development environments, significantly reducing deployment risk.
Built comprehensive CI/CD pipelines in GitHub Actions for automated testing and deployment.
Delivered ad hoc data analysis supporting critical business decisions.

Data Tech Specialist | ACC | Wellington, NZ

Sept 2022 - Aug 2024

Co-architected and developed enterprise MLOps framework (MLflow, Docker, R, Python).
Designed containerisation strategy for R and Python models with inference store + logging.
Architected model serving infrastructure via REST API supporting batch + on-demand processing.
LLM serving: Designed containerised LLM solutions (Ollama), implemented RAG with vector DBs, custom middleware.
Architected and built auto-versioning ML model store in Python with Azure Blob backend.
Designed ETL architecture in Python, ingesting Parquet, JSON and CSV to Snowflake.
Developed CLI Python application for auto-generating and linking dbt documentation.
Built GUI Python application for editing dbt model files.
Designed reusable dbt ingestion pipelines and validation macros.
Snowflake infrastructure deployment with Terraform.

Senior Data Engineer | New Zealand Post | Wellington, NZ

July 2021 - Sept 2022

Led migration of multiple legacy on-prem systems (Oracle, SQL Server) to Snowflake.
Built integrations with Active Directory and multiple SaaS providers.
Developed comprehensive ETL pipeline architecture (Snowflake, AWS Lambda, dbt).
Designed and deployed enterprise cloud infrastructure with Terraform.
Handled high-volume streaming data processing (Kafka, S3).
Built multiple bespoke API connectors for real-time data ingestion.
Created CI/CD pipelines dramatically reducing deployment time and risk.
Collaborated with data scientists to deploy production ML models.
Mentored junior engineers, significantly improving team capabilities.

Senior Data Analyst | Ministry of Justice | Wellington, NZ

Dec 2020 - July 2021

Led setup/configuration of a new RStudio Server installation for analyst teams.
Liaised with analysts and BI team to define technical requirements and workflows.
Significantly improved security protocols and user experience.
Delivered comprehensive R training to technical staff.

R Developer | Ministry for Primary Industries | Wellington, NZ

Feb 2020 - Dec 2020

Translated NZ's complex agricultural greenhouse gas emissions model from Excel/VBA to R.
Delivered complete solution including comprehensive code, documentation, and unit tests.
Implemented performance optimization (caching), robust input validation, and dependency tracking.
Delivered large-scale project on-time and to specification.
Ensured knowledge transfer and continuity planning.

Junior ML & Data Engineer | Hargreaves Lansdown | Bristol, UK

Jan 2018 - Sept 2019

Migrated legacy databases to Hadoop cluster.
Built ETL/data models (Hive, Impala, Sqoop).
Increased marketing conversion rate by 25% with ML propensity model.
Deployed R Shiny app for customer support.
Built forecasting models.
Trained analysts in R and Python.

Operations MI & Reporting Manager | Hargreaves Lansdown | Bristol, UK

Dec 2015 - Jan 2018

Built and led a new MI/reporting team from ground up.
Architected processes that significantly improved operational efficiency and reduced risk.
Provided technical leadership for risk management and regulatory compliance initiatives.

Customer Support & Team Leadership | Hargreaves Lansdown | Bristol, UK

Feb 2011 - Dec 2015

Progressed from Customer Support to Team Leader (2013) to Operations MI Manager (2015).

Education

City & Guilds Level 3 Award in Leadership and Management (Distinction) - National Skills Academy for Financial Services (2016)
Postgraduate Certificate: Renewable Energy and the Built Environment - University of East London (2012-2013)
BSc (Hons) Chemistry - University of Bristol (2007-2010)

References

Available on request.