Machine Learning Engineer

Machine Learning Engineer London onsite to £110k Do you have expertise with Machine Learning in production? You could be progressing your career at a London based tech start-up with £5 million in recent pre-seed funding, in an impactful role that you'll shape. The product is an AI agentic based platform that writes production grade code. As a Machine Learning Engineer you'll take open-source LLMs (code and general models) and turn them into high-performance software engineer agents using supervised fine tuning and large scale reinforcement learning.

This isn't prompt engineering. You'll design and run serious training experiments across multi-node GPU clusters, build RL loops where models write code and get rewarded (or penalised) by real test outcomes and push long-context and MoE style architectures to their limits. You'll work hands-on across the full stack: custom PyTorch dataloaders, distributed training (DDP/FSDP), experiment tracking, debugging NCCL issues at 2am, and squeezing performance out of multi-GPU jobs.

You'll help design opinionated reward functions that reflect what great engineering actually looks like, not just benchmark scores.