Job Title: Principal AI Engineer (LLMs, Agentic AI, Graph Neural Networks) Location: UK-based (London preferred) Type: Contract (Outside IR35) Duration: 2 years Start Date: ASAP Rate: Market Competitive About the Opportunity We’re hiring a Principal AI Engineer on behalf of a globally recognised technology leader. This is a 2-year Outside IR35 contract working through an approved services supplier on the buildout of next-generation AI infrastructure that blends LLMs, autonomous agents, and graph intelligence into production-ready systems. This is a high-impact role for someone ready to lead technical design, own delivery, and collaborate with world-class researchers and engineers. Key Responsibilities • Design, fine-tune, and evaluate domain-specific LLMs (GPT, LLaMA, Mistral etc.), incorporating RAG and prompt engineering • Architect and deploy multi-agent systems using AutoGen, LangGraph, CrewAI, LangChain • Build and maintain knowledge graphs and implement graph neural networks (GNNs) for real-time inference and reasoning • Develop APIs and services (REST/gRPC/event-driven) for secure LLM deployment • Lead implementation of ML pipelines, distributed training, and model optimisation • Ensure alignment with AI safety, privacy, and ethical standards Requirements • MSc/PhD in Computer Science, Machine Learning, or related field – or equivalent commercial experience • 5+ years in AI/ML/Data Science with strong delivery in production environments • Advanced Python skills with deep experience in PyTorch, TensorFlow, or JAX • Demonstrated expertise in LLM training/fine-tuning (multi-billion-token corpora, RLHF, DPO) • Production use of agentic frameworks, including autonomous task planning and tool orchestration • Strong experience with GNN libraries (PyTorch Geometric, DGL), graph DBs (Neo4j, TigerGraph) • Infrastructure experience with Spark/Flink, cloud platforms (AWS/GCP/Azure), and Kubernetes/Terraform Nice to Have • Experience with model optimisation (quantisation, pruning, distillation) • Open-source contributions, peer-reviewed publications, or patents Why Apply? • 2-year Outside IR35 contract • Build cutting-edge AI systems that blend LLMs, agents, and graphs • Join a forward-thinking team focused on innovation, performance, and real-world impact • Influence future-facing AI applications across domains