Islay Robinson explains how a bespoke interest-only mortgage at circa 70% LTV helped secure a prime London property for high-net-worth clients.

The clients knew exactly what they wanted: a prime London residential property financed at approximately 70% loan-to-value on an interest-only basis over a 20-year term.

They had the income, the assets, and a clear strategy for repaying the capital over time.

What they did not have was a mainstream lender willing to support the structure.

That is rarely surprising.

A large residential mortgage on a fully interest-only basis sits in a part of the market most high-street lenders simply do not serve. The combination of significant loan size, long-term interest-only borrowing, and wealth-based underwriting rules out much of the market before an application is even submitted.

This is where structuring matters.

When this case came to us, the challenge was not whether finance was available. It was identifying the right lender and ensuring the structure aligned with what the clients were actually trying to achieve.

The clients were not looking for the cheapest headline rate. They wanted flexibility, low monthly servicing costs, and a facility that worked alongside their wider wealth strategy.

We introduced a specialist private bank with genuine appetite for high-net-worth residential lending. More importantly, the bank understood the clients’ financial profile and was willing to assess the full picture rather than relying on conventional affordability metrics.

A bespoke long-term mortgage was structured at approximately 70% loan-to-value on an interest-only basis over 20 years. The facility was designed to keep monthly payments efficient while preserving liquidity across the clients’ broader investment portfolio.

Crucially, the structure also provided flexibility to reduce or redeem the borrowing early should circumstances change. That mattered. The clients wanted optionality, not restriction.

The mortgage offer was secured within the required timeframe, giving the clients certainty and allowing them to complete the acquisition on their preferred schedule.

The point I always come back to on transactions like this is the difference between complexity and difficulty.

On paper, this deal looked complex. Large loan. Interest-only. Leasehold property. High-net-worth underwriting.

In reality, it was straightforward because the clients were well prepared, the repayment strategy was credible, and the right lender was available.

That is often what separates a successful transaction from a failed one.

At this level, the biggest risk is rarely the structure itself. It is approaching the wrong lender with the wrong positioning.

Certainty of execution matters more than anything else.