Otterpool Park Infrastructure Costs: £374m Inflation-Adjusted Benchmark for 8,500 Homes

There’s a number buried in another major Kent housing battle which deserves much more attention in Folkestone & Hythe.

£36,500 per home.

That’s what a viability expert working for Quinn Estates told the Highsted Park planning inquiry in May 2025 was the approximate infrastructure cost at Otterpool Park, based on a scheme of 8,500 homes from the modelling in 2021. The evidence was given by chartered surveyor Tim Mitford-Slade of Strutt & Parker, who used Otterpool as a local comparison when assessing the enormous Highsted proposals around Sittingbourne.

Multiply £36,500 by 8,500 homes and you get £310.25 million for infrastructure costs for all 8,500 homes.

But here’s the important bit.

That £36,500 figure comes from the older viability modelling. Gerald Eve’s June 2021 master-developer appraisal recorded £287.008 million within the relevant construction cost schedule and another £27.332 million of infrastructure risk. Together that comes to about £314.34 million — £36,981 for each of 8,500 homes.

In other words, Quinn’s £36,500 comparator wasn’t some wildly different number appearing from nowhere in 2025. It sits within about £481 per home — just 1.3% — of the figure produced by Otterpool’s 2021 modelling.

And 2021 prices aren’t 2026 prices.

The Building Cost Information Service said in early 2022 that civil-engineering costs were expected to rise 15% between the third quarter of 2021 and the third quarter of 2026, while civil-engineering tender prices — closer to what clients encounter when work actually goes to market — were forecast to rise 22% over the same period.

Apply those two benchmarks to Otterpool’s £36,981-per-home figure and the picture changes considerably.

At a 15% uplift, it becomes about £42,528 per home.

At 22%, it becomes about £45,117.

That gives a sensible inflation-based range today of roughly £43,000 to £45,000 for every home.

There’s a useful independent cross-check. The RICS Community Infrastructure Levy Index, produced by BCIS from its All-in Tender Price Index, stood at 333 in 2021. For 2026 it’s 400. Apply that movement to Otterpool’s £36,981 and you arrive at approximately £44,422 per home. The CIL index isn’t a dedicated civil-engineering index, so we wouldn’t use it alone, but it lands almost slap bang in the middle of the range.

So take a central working figure of about £44,000 per dwelling.

Across 8,500 homes, that’s roughly £374 million.

That’s around £64 million more than the £310.25 million implied by Quinn’s £36,500 comparator.

And the pressure hasn’t disappeared. Turner & Townsend’s latest UK construction forecasts put infrastructure tender-price inflation at 4.5% in 2025 and 5% in 2026, while BCIS reported civil-engineering tender prices rising another 2% between the first and second quarters of 2026. Labour, specialist skills, energy and procurement risk all remain capable of pushing infrastructure bills upwards.

There’s an important warning here.

We aren’t saying Otterpool’s current infrastructure bill is £374 million.

FHDC and Homes England haven’t publicly released the current detailed infrastructure cost plan or the financial model now being used as they pursue substantial public-sector support for Otterpool. The £374 million is an inflation-adjusted benchmark based on the historic viability evidence — not a substitute for the missing current cost plan.

And the eventual number could move either way as designs, specifications, phasing and infrastructure requirements change.

But one thing looks increasingly difficult to defend.

£36,500 per home is no longer a sensible 2026 benchmark for infrastructure originally costed around 2021.

A realistic present-day equivalent appears closer to £43,000–£45,000 per home — roughly £365 million to £383 million across 8,500 homes.

And with Homes England now involved in a Treasury funding bid intended to support the wider Otterpool development, that raises the obvious question.

What does the current infrastructure cost plan actually say — and how much of the bill could ultimately fall on the public purse?

The Shepway Vox Team

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