Building a B2B prospect list from scratch costs nothing but time if you know where to look. The problem is that most teams skip the methodology and jump straight into buying a list from a data broker - only to discover that 30% of the records are outdated and half the contacts are irrelevant to their ICP.
This guide walks through the process of building a UK-focused B2B prospect list using free and low-cost sources. It assumes you are starting from zero and want a list you can actually trust.
Step 1: Define Your Ideal Customer Profile
Before you search for a single company, write down exactly what a good prospect looks like. An ideal customer profile is not a vague description. It is a set of filterable criteria.
At minimum, define:
- Industry vertical: SaaS, financial services (strong in Leeds and Edinburgh), manufacturing (concentrated in Sheffield, the Midlands, and the North West), professional services, etc.
- Company size: Headcount range (e.g., 50-200 employees) or revenue band
- Geography: UK-wide, specific regions, or specific cities
- Company status: Active, trading, not dissolved or dormant
- Target persona: Job titles, seniority levels, and departments you sell to
- Disqualifiers: Company types you do not sell to (charities, public sector, pre-revenue startups)
Write these down before proceeding. Every step that follows uses these criteria as filters.
Step 2: Companies House (Free)
Companies House is the single most underused prospecting source in the UK. Every limited company registered in England, Wales, Scotland, and Northern Ireland is listed with structured, searchable data.
What you can get from Companies House data for sales:
- Company name and registration number
- Registered address
- SIC codes (Standard Industrial Classification - the closest thing to a filterable industry field)
- Company status (active, dissolved, dormant, in liquidation)
- Incorporation date (useful for filtering by company maturity)
- Filing history (accounts filings show turnover bands for some companies)
- Officers and directors (names and appointment dates)
The free Companies House search at beta.companieshouse.gov.uk lets you search by name. For bulk work, the Companies House API is free with registration and allows programmatic searching by SIC code, location, and status.
Use SIC codes to filter by industry. Cross-reference with your ICP criteria. Export active companies that match. This gives you a company-level list - you will add contacts in later steps.
Step 3: LinkedIn (Free to Low Cost)
With your company list from Companies House, move to LinkedIn to identify the people at those companies you need to reach.
Free LinkedIn search lets you filter by company, job title, and location. LinkedIn Sales Navigator (£60-80 per month) adds filters for headcount, department size, years in role, and recent job changes.
For each target company, search for your target personas. If you sell to Heads of Marketing at SaaS companies, search for that title at each company on your list. Record: full name, current job title, company, and LinkedIn profile URL.
Two things to watch for:
- Job title accuracy: LinkedIn profiles are self-reported. "Head of Growth" might be a team of one at a 20-person startup or a VP-level role at a 500-person company. Check the company size to calibrate.
- Activity signals: A prospect who posts regularly on LinkedIn is more likely to see and respond to outreach than one whose last activity was 18 months ago.
Step 4: Apollo, Lusha, or Similar Tools (Low Cost)
With company names and contact names identified, you need verified email addresses and phone numbers. LinkedIn does not provide these directly (connection requests aside), so you need a contact data tool.
Apollo.io, Lusha, and similar platforms let you search by company and contact name to retrieve work email addresses and direct dial phone numbers. Most offer a free tier with limited credits, then charge £30 to £100 per month for more volume.
When using these tools:
- Verify email addresses through the tool's confidence scoring. Only export emails rated 90%+ confidence.
- Cross-reference phone numbers with LinkedIn profiles to confirm the contact is still at the company.
- Check that the data provider is GDPR compliant and can demonstrate their lawful basis for processing the data.
Do not export every contact you find. Only export contacts that match your ICP criteria. A smaller, accurate list outperforms a large, untargeted one on every metric.
Step 5: Trade Directories and Industry Sources
For niche industries, generic tools miss the best prospects. Trade directories and industry-specific sources fill the gap.
Examples for UK markets:
- Crunchbase: Funded startups with investment data, useful for targeting companies with budget
- G2 and TrustRadius: Companies using specific software (filter by tech stack if you sell to teams using particular tools)
- Industry association membership lists: Many trade bodies publish member directories with company details
- Conference and event attendee lists: Past sponsors and exhibitors at industry events are often high-intent prospects
- Government contract databases: Contracts Finder shows companies winning public sector work, indicating revenue and capability
These sources are manual and time-consuming to work through, but they produce high-quality, contextual records that generic databases miss entirely.
Step 6: Job Boards as Intent Signals
A company hiring for a specific role is often a buying signal for related services. If a company is hiring its first Head of Sales, they probably need CRM setup, data, and outbound infrastructure. If they are hiring SDRs, they need prospect lists.
Monitor job boards (LinkedIn Jobs, Indeed, Adzuna) for hiring patterns that align with your offering. A company posting three SDR roles in Manchester is expanding their sales team - and likely needs the data infrastructure to support it.
This is not a primary list-building source, but it is a powerful enrichment layer. Adding a "hiring signal" field to prospect records helps reps prioritise outreach to companies with active, relevant needs.
Step 7: Assemble and Clean
You now have data from multiple sources that needs combining into a single, clean list. This is where most teams make mistakes.
- Deduplicate: Match on company name (normalised) and contact email. Merge records from different sources, keeping the most complete version of each field.
- Validate emails: Run every email through a verification service (NeverBounce, ZeroBounce, or similar). Remove any address that does not pass validation.
- Standardise formats: Consistent country field ("United Kingdom"), consistent phone format (+44), consistent job title capitalisation.
- Score against ICP: Rate each record on how closely the company and contact match your ideal customer profile. Prioritise outreach to the highest-scoring records.
- Check GDPR compliance: Ensure you have a lawful basis for contacting each person. For B2B prospecting under GDPR, legitimate interest is valid but must be documented.
If this assembly and cleaning step feels like more work than the prospecting itself, that is because it is. Data assembly and cleaning is where most prospect lists fail - the research is solid but the execution is sloppy. If you need this done at scale, a pipeline build service handles the entire process from ICP definition through to a CRM-ready, verified list.
What Good Looks Like
A well-built UK B2B prospect list has:
- Email bounce rate under 3%
- Direct dial accuracy above 80%
- Every record matched to ICP criteria with a confidence score
- Companies House validation confirming active company status
- Consistent formatting across all fields
- GDPR documentation for lawful basis of processing
Building this from scratch for 500 to 1,000 records takes a single person roughly 40 to 60 hours. For 5,000+ records, the manual approach becomes impractical and you need either tooling or outside help.
Start small. Build 200 records using the process above. Test your outreach on that list. Refine your ICP based on what converts. Then scale the list-building process once you know which prospects actually respond.
