Most high-net-worth principals operate across both sides of the personal/commercial line. The home, the cars, the jewellery, the art collection sit on personal-lines policies. The trading business, the company premises, the staff, the professional liability, the cyber exposure sit on commercial-lines policies. Both are essential. They are also structurally different products that benefit from different underwriting desks — even when the principal is the same individual.
This guide explains where the line actually runs in 2026, the six boundary cases we see most often at Mayfair, and how the group structure routes work to the correct desk without duplicating premium or leaving gaps at the boundary.
Why the Line Matters
Insurance is priced by exposure, not by policyholder. A high-net-worth household at Mayfair is treated as an HNW personal-lines risk and priced accordingly. The same individual’s trading business is a commercial-lines risk and priced on a completely different basis — turnover, employee count, professional exposure, industry sector. Trying to fit both onto a single “everything-included” policy means either over-paying on the personal side or under-protecting on the commercial side. Usually both.
Specialist desks coordinated under a common umbrella solve this: each policy sits on the right desk, priced correctly, and the wordings are written to align at the boundary rather than overlap or conflict.
The Six Bridging Cases We See Most Often
1. The director with personal valuables. The most common scenario. The principal has an HNW home portfolio at Mayfair (combined property, scheduled valuables, prestige cars). The trading company holds its own assets — office premises, equipment, IP, staff — via our commercial sister brokerage. Both desks talk to each other when the principal also uses company-owned assets personally (the car driven for both purposes, the home that’s also the registered office of a smaller subsidiary).
2. The home-based founder. The home stays on a Mayfair combined HNW policy. The business operation — client liability, professional indemnity, cyber, office equipment — moves to Kensington as a small commercial package. The boundary is the activity, not the address: anything done for commercial gain at the property is a commercial exposure, separate from the home itself.
3. The buy-to-let portfolio with mixed-use property. Residential lets sit at our personal-lines sister brokerage for standard residential landlord cover. Once any unit is let to a business tenant — office, retail, light industrial, mixed-use — the placement moves to Kensington’s commercial property owners insurance. A portfolio with both sees both desks.
4. The employer of domestic staff. Households employing housekeepers, nannies, drivers, or estate staff have an employer-liability obligation that’s legally identical to a commercial employer — but structurally different. The cover form is personal-lines, placed through Chelsea, even though the underlying legal exposure is the same. For larger estate operations with multiple staff, the placement may move to a hybrid wording managed jointly with Kensington.
5. The professional firm with HNW partners. The firm’s professional indemnity, cyber, employer liability, and office package sit at Kensington as standard commercial cover. The partners’ personal-lines portfolios — jewellery, fine art, prestige cars, combined HNW home — sit at Mayfair. Where the firm carries directors’ and officers’ cover for personal liability of partners, the wording is coordinated so there are no gaps between commercial D&O and personal HNW.
6. The trust or family-office structure. Family offices typically hold a mix of trust-owned property, personally-owned property, and operating-company assets. Each strand belongs at a different desk: trust-owned high-value property at Mayfair, operating-company assets at Kensington, personally-owned valuables at Chelsea or Mayfair depending on category. Family offices benefit from a consolidated review across all three desks once a year so the placements stay aligned with the actual asset map.
What Doesn’t Need to Move
It’s worth being explicit about what stays at Mayfair. Owning a business does not move your personal HNW cover. If you are a principal with a high-value home, scheduled valuables, prestige cars, and a private healthcare arrangement, those exposures are personal-lines and they stay at Mayfair regardless of how the trading business is structured. The split is exposure-by-exposure, not policyholder-by-policyholder.
Most HNW principals end up with policies on multiple desks: personal HNW combined at Mayfair, single-item category-specialist cover at Chelsea where individual items justify it, and the full commercial portfolio at Kensington. The three desks coordinate so the wordings don’t overlap or leave gaps at the boundary.
How the Coordination Actually Works
Same FCA reference (445714), same Mayfair office, same compliance team. From a client’s point of view it looks like three conversations with three different specialists at the same firm — because that’s what it is. We share basic client information across the desks (with explicit consent), avoid duplicating onboarding questions, and align renewal dates where useful so the three policies are reviewed together each year.
Importantly, none of the desks pay or receive referral fees between them. Each placement is priced on its own commercial merits, and we will tell you honestly when a given exposure belongs at a different desk than the one currently holding it.
Five Questions to Stress-Test Your Current Cover
1. Is any part of my current home policy quietly funding business activity? Home offices, work tools, business equipment kept at home.
2. Is any commercial policy quietly relying on personal arrangements? Director-owned vehicles used for business, personal devices used for professional work, personal premises hosting business activity.
3. Are there gaps at the boundary? The most common gap is the moment an asset transitions from personal use to commercial use — or vice versa.
4. Are there overlaps? Two policies covering the same asset usually means one is paying premium for nothing — or both will dispute liability at claim.
5. Has the exposure profile drifted since the last review? New business activity, new properties, recent liquidity events, new staff — all common triggers for the existing structure to need a refresh.
Where to Start
If you suspect any of the five questions apply, the right starting point is a single conversation with Mayfair. We can place the personal-lines portion, route the commercial portion to Kensington, identify any single-category specialist work that belongs at Chelsea, and make sure the wordings work together. Get in touch — one conversation usually settles it.