A Second Runway and 100 Million Guest Nights: Why the Gatwick Diamond Is About to Get Very Interesting for Short Term Lets

Forty-three million passengers a year. That's roughly where Gatwick sits today. Now picture 75 million, maybe 80 million, by the late 2030s. That's not a rounding error — that's nearly double the airport on our doorstep, and it's coming.

In June this year the High Court upheld the Government's approval for Gatwick's Northern Runway project — a £2.2 billion, privately financed scheme to bring the existing standby runway into full daily use alongside the main one. It's expected to add £1 billion a year to the local economy and create around 14,000 jobs across the region, according to Gatwick's own figures. Jet2 has already based six aircraft at Gatwick from March this year, flying to 29 destinations. This isn't a planning document sitting in a drawer. It's happening.

I mention all this because I live and work in it. Lime Finance Solutions is based at the Rutherford Centre in Crawley — practically under the flight path — and I've watched the Gatwick Diamond change shape over three decades. Crawley, Horley, Horsham, East Grinstead, Reigate — this whole patch is about to feel the effects of that second runway in ways that go well beyond the airport perimeter.

Where This Meets the Short Term Let Market

Nationally, short term lets had a big 2025. The ONS recorded over 100 million guest nights booked through online platforms last year, up 11.5% on 2024. That's a serious asset class now, not a side hustle for people with a spare cottage — I wrote about what that means for the market more broadly a few weeks back.

The Gatwick Diamond has its own version of that story, and it's arguably more resilient than most. This isn't a market that lives and dies on summer tourism. Crawley pulls in contractors, corporate travellers, aviation staff and training delegates all year round. Horley sits right on the airport's doorstep and does well out of pilots and aviation trainees needing a base for weeks at a time, not just a night. Gatwick itself generates a steady stream of overnight stays from delayed passengers, aircrew and business travel that has nothing to do with school holidays.

A second runway means more flights, more crew rotations, more contractors building and maintaining the infrastructure, and more businesses setting up near an airport that's about to nearly double in capacity — the kind of local building boom I see funded through property development finance time and again. Every one of those things needs somewhere to stay that isn't a hotel room booked six months in advance at inflated rates.

My daughter Megan works in construction health and safety — she's an asbestos surveyor, so she spends a fair bit of her working life on-site at developments up and down the country, often staying locally for the duration of a job. Multiply her by the thousands of engineers, project managers and specialist contractors who'll be working on Gatwick-related infrastructure and the wider building boom that follows an airport expansion, and you start to see why serviced accommodation operators in this area are rubbing their hands together. That's not seasonal demand. That's a construction and infrastructure cycle that runs for years.

The Bit Nobody Tells You: Financing These Properties

Here's where it gets interesting from where I sit. For a long time, high street lenders simply didn't know what to do with a short term let. Standard buy-to-let mortgages are built around an assured shorthold tenancy — a fixed tenant, a fixed monthly rent. An Airbnb or serviced accommodation property doesn't look anything like that on paper, even if the numbers underneath are excellent.

I spent nearly 20 years on the banking side before I set up Lime, and I remember exactly this conversation happening on repeat. The properties weren't bad investments. The lenders' systems just weren't built to read them. Variable nightly income, platform dependency, occupancy that swings between a quiet Tuesday and a fully booked half-term week — none of that fits a spreadsheet designed for salary multiples and fixed rents.

That's changed, and it's changed for the better. Specialist and challenger lenders have built proper underwriting around this sector now. They want to see demonstrated gross income, realistic occupancy figures rather than the owner's best-case projections, and a genuine trading history — ideally supported by platform analytics and at least a year or two of accounts. It's more thorough than a standard buy-to-let application, but it's also more honest, because it reflects what the property actually earns rather than what a tenancy agreement says it should earn.

A few things I'd flag to anyone looking at this near Gatwick specifically:

Check the lease before you fall in love with the flat. A freehold house gives you far more lender choice than a leasehold flat, particularly if the lease has the words "no holiday lets" buried in it, or needs freeholder consent. I've seen deals collapse at the eleventh hour over exactly this. Sort it before you offer, not after.

Document your income properly from day one. A client telling me their property earns £4,000 a month during peak contractor season is one thing. What does it earn in a quiet January? Lenders will want the average across a full year, not the best month cherry-picked for the application.

Think about your exit. If demand around Gatwick shifts — a change in local regulation, a dip in construction activity once the runway work is complete — could the property revert to a standard letting, or sell easily as residential? Lenders think about this. So should you.

Rates have improved, and they'll likely keep improving. Eighteen months ago the product range for short term lets was thin and expensive — often a full percentage point above equivalent buy-to-let rates, if you could find a lender willing to look at it at all. That gap has narrowed as more specialist lenders have entered the market, drawn in by exactly the kind of sustained, non-seasonal demand a growing Gatwick creates.

What This Means If You're Thinking About It

If you already hold serviced accommodation in the Gatwick Diamond, this is a good moment to review your finance rather than assume your existing deal is still the best one available. The lender landscape has moved a long way in a short time, and a broker who knows this patch and this sector can often find you a materially better rate than the one you took out two years ago.

If you're considering buying into this space for the first time — perhaps because you can see exactly what a second runway does to demand in Crawley, Horley or Horsham — talk to someone before you make an offer. The financing for a short term let isn't the same as a standard buy-to-let, and the details that trip people up (the lease, the income evidence, the exit route) are all sortable in advance if you ask the right questions early.

I've been financing property around this airport for the best part of three decades, through a fair few ups and downs neither Gatwick nor I saw coming. A second runway and a doubling of passenger numbers is about as clear a signal as this market ever gives you. If you want to talk through what that means for a specific property or a specific plan, I'm always happy to have that conversation.

David Farmer Lime Finance Solutions