Stretch.CodesLondon

AI agents that actually work in production.

I’m Andrew, a contractor with over a decade of experience. I build AI agents, LLM pipelines and the apps around them, and I join your team until it’s live and handed over.

Taking on new contracts

Clients

  • RWS
  • Zoopla
  • Monzo
  • Which?
  • Eurostar
  • AND Digital
  • Reward Gateway

What I do

Selected work

  1. 01

    RWS

    Patent drafting agent

    Attorneys upload an invention disclosure and get a draft patent back, then refine the claims with it.

    My part

    Built the ingestion, the pipeline and the prompts, plus the adversarial reviews that pull each draft apart before an attorney sees it.

    per patent draft
    5 hrs → 10 min
  2. 02

    Zoopla

    Agentic property search

    Property search you do by chatting with an agent. It started as a proof of concept and it’s live on Zoopla now.

    My part

    1. PrototypeBuilt a proof of concept with a designer and put it in front of real users.

    2. ListenReshaped it around what the user research found, a sprint at a time.

    3. ScaleTook it to a wider team. More tools on the MCP server, and a proper agent harness.

    4. ShipHuman-in-the-loop, chat widgets and better context, so it’s good to use and not just a demo.

    monthly visits to Zoopla
    27M
  3. 03

    Which?

    Personalised content

    Personalised content for Which? members.

    My part

    Built the AWS services behind it, from proof of concept to production.

    people a day
    100k+
  4. 04

    Eurostar

    Booking system rebuild

    Two years replacing the old booking system and the agent portal.

    My part

    Worked on the rebuild, and led a team of six moving the vouchers onto a new, secure service.

    bookings a day
    55k
    of vouchers moved
    £80m
    faster to book
    25%

Also worked with

  • Monzo

    Internal tools that took a pile of manual work off the ops team.

  • AND Digital

    Till software for 300+ restaurants, then an ordering and payments app. Two teams, about twelve engineers.

  • Ember

    Accounting software on web and mobile, in Node, React Native and Postgres.

  • Quander Digital

    Interactive technology for live events, including YouTube Brand Casts.

  • Young & Shand

    Social and marketing sites in WordPress and React.

  • Reward Gateway

    Rolled a bunch of separate web apps into one, on a shared UI library.

Side projects

  • Agentic Accountant

    An AI accountant for my own company. It reads my books in FreeAgent, answers questions about them and drafts emails to my real accountant.

    Agents · Tool design · HMRC API · FreeAgent · Gmail API

  • ReturnSorted

    Self-assessment tax returns without the headache. HMRC sign-in, magic-link login and Stripe, built end to end.

    Next.js · Vercel · AWS Lambda · Supabase · Stripe

I write about what I learn along the way. Read the blog

What I work with

I’ve worked with Eurostar, Monzo, Which? and plenty more. These days I build agentic AI platforms, and I care most about the quality of what they put out.

AI & agentic systems

  • LLM application development
  • Agent loops & LLM harnesses
  • Agent orchestration (LangGraph / LangChain)
  • Tool design & MCP servers
  • Prompt engineering
  • Context engineering
  • RAG & retrieval pipelines
  • Human-in-the-loop pipelines
  • Adversarial review & verifier agents
  • Multi-agent orchestration
  • Hallucination & sycophancy mitigation
  • Evals & LLM-as-judge
  • Tracing, monitoring & observability
  • Token & cost instrumentation
  • Guardrails & output validation
  • Anthropic & OpenAI APIs · AWS Bedrock
  • Agentic dev tooling (Claude Code)

Core engineering

  • TypeScript / JavaScript
  • React / React Native
  • Next.js / Node.js
  • GraphQL
  • AWS / Terraform / DevOps
  • Python / Go / PHP
  • MySQL / Postgres / MongoDB
  • Unit & integration testing
  • Auth0 / OAuth 2.0

Contact

What are you building?

Tell me where it’s got stuck. If I’m not the right person for it, I’ll say so.