SR2About this role
Research Scientist / Engineer - LLM Post-Training
London - Hybrid
I'm hiring for an AI start-up focused on continual learning. They're looking for a Research Scientist/ Engineer to lead large-scale experimentation across supervised fine-tuning, reinforcement learning, distillation and repeated model adaptation.
You will take ownership of research questions, design training programmes and work directly with multi-billion-parameter language models.
What you’ll work on
Train and post-train large language models.Design supervised fine-tuning and reinforcement-learning experiments.Research continual and sequential model adaptation.Build datasets, curricula and training-data mixtures.Evaluate capability improvements, retention and regressions.Work with distillation, synthetic data and model-generated training data.Develop RL environments and verifiable-reward tasks.Diagnose training failures and unexpected model behaviour.Build reliable experimentation and evaluation infrastructure.Collaborate with researchers developing new learning algorithms.
What we’re looking for
Substantial hands-on experience training or post-training language models.Experience with SFT and reinforcement learning for LLMs.Knowledge of modern policy-optimisation methods.Experience with distributed or multi-GPU training.Strong Python and PyTorch, JAX or equivalent framework experience.Understanding of training dynamics, evaluation and generalisation.Ability to own research directions rather than only implement predefined approaches.
Particularly valuable experience
Working with models in the 10B+ parameter range.Running substantial multi-node training jobs.Continual learning or repeated model adaptation.Distillation and synthetic-data generation.Reinforcement learning with verifiable rewards.Dataset construction and curriculum design.Building evaluation systems that detect capability loss and regression.
A PhD is valuable but not essential. Direct evidence of successfully training, adapting and evaluating large models is the primary requirement.
Why join?
Work on fundamental problems in language-model adaptation.Run ambitious experiments with direct influence over the research roadmap.Join a small, highly technical team at an early stage.Take meaningful ownership over both research and implementation.Receive a highly competitive salary and significant equity.
Please apply directly or drop your CV over to 
Company:
SR2
Level of experience (years):
Senior (5+ years of experience)
How to apply:
Please mention NLP People as a source when applying