GTM Data Engineer: Waterfall Enrichment & List Building for M&A - Technical Expert Needed

We are a VC-backed M&A advisory firm in London. We sell essential-service businesses (fire safety, building services, FM, healthcare). We need one technical operator to own our data engine: building, enriching and cleaning lists of companies and their owners, and keeping our outbound infrastructure healthy. This is a systems role, not admin. If you think in pipelines, dedup logic and match rates, read on. If you think "I'll research your leads manually," this is not for you. What you will do - Aggregate leads from all our sources into one clean, deduplicated pipeline - Build two list types: seller/target companies (owner-operated, essential-service) and buyer/acquirer universes (PE, search funds, roll-ups, strategics, family offices) - Find and verify two decision-maker contacts per company. If the first pass misses one, you go and find it. - Build and maintain Clay (or other company + contact data enrichment waterfalls: chain providers in order, clean before enriching, protect credits - Surface signals with AI agents, scrapers and APIs: founder or director age, succession, performance, location - Write natural, native-English personalisation lines for US and UK owners, many running 50-70 year old family firms (we have custom claude skills and examples ready for you to learn from) - Own email deliverability across Google and Microsoft (SPF, DKIM, DMARC, warmup, inbox placement) - Manage WhatsApp Business API outbound: quality rating, tiers, opt-in discipline, number health - Clean and maintain our CRM so it stays accurate and current Deliverables - Lemlist-ready CSVs in a fixed ~30-column schema we provide, camelCase, zero data loss, verified - Weekly enrichment output tied to live campaigns - Proactive email and WhatsApp health flags, before anything breaks - A short methodology note per list: sources, waterfall order, exclusions You must have - Built and enriched lists of small, owner-operated local and essential-service companies (plumbing, electrical, fire safety, HVAC, security, the 50-70 year old boomer-owned type), using Google Maps scraping, Clay, and multi-source enrichment. M&A, brokerage, PE, search fund or roll-up experience is a strong plus, not required, if your list-building on these company types is strong. - Expert Clay (or another similar platform), including waterfall enrichment, filtering, dedup and computed columns - Expert Lemlist or a direct equivalent - Fluency with MCPs, APIs, AI agent prompting, and stitching tools into one reliable workflow - Email deliverability expertise current as of 2026 (Google and Microsoft enforcement, SPF 10-lookup limit, warmup, bounce and complaint thresholds) - Native or fluent English, shown in writing and verbally Strong plus WhatsApp Business API experience, or clear evidence you learn technical systems fast Python or SQL, Companies House or US registry and licence-board sourcing Who you are Obsessive on detail. Dedup, two contacts per company, verified data. Analytical and systems-minded, not a creative generalist Patient. This is continual enrichment of the same lists to a rising standard, not one-and-done How I work, and what I expect Structured comms. Ability to communicate what you will do and the process. During: progress. After: what you did and the output. Surface blockers instantly. Blocked on credits, a tool, access or a decision? Tell me the specific thing you need. I unblock fast. I pay for whatever subscription or credits you need. In return, raise it fast, do not sit on it, do not quietly deliver less. Be direct. No wishy-washing, no "it depends" without a recommendation. Disagree? Say so and say why. Have a backbone. Take instructions, execute accurately, push back with reason. I want a reliable operator with a spine, not a yes-machine and not someone who goes silent when stuck. Access provided: Claude account and credits, Lemlist, Clay, WhatsApp Business API, relevant MCPs and API keys, plus any subscription or credits you need to do the job well.