A site that exists on paper but not yet on the ground
On the western edge of the A1 dual carriageway, roughly two miles south of Grantham town centre, a 35.5-hectare field sits allocated but empty. King 31 — named for its position within the South Kesteven Local Plan — is earmarked for up to 140,000 square metres of B2 and B8 floorspace: the planning shorthand for general industrial units and large-scale storage and distribution warehousing. In practical terms, that means factory sheds, logistics hubs, and the kind of last-mile delivery infrastructure that has reshaped employment land across the East Midlands over the past decade.
Developer Mulberry Commercial secured outline planning permission from South Kesteven District Council on 19 March 2026 (reference S25/0505). Managing director Phil Jones cited the site's direct A1 frontage and what he described as Grantham's 'emerging status as a regional hub' as the investment rationale. Both claims have reasonable grounding: the A1 corridor between Newark and Stamford is an established logistics axis, and Grantham's housing growth — rapid and largely residential in character — has sharpened the case for employment land that can offer local jobs at scale.
But outline permission is the planning system saying yes in principle, not a green light for machinery. At King 31, all matters except access remain reserved, meaning design, layout, scale, landscaping, and appearance must each return to committee before any building can begin. The Section 106 legal agreement — which will bind the developer to infrastructure contributions and other obligations — has not yet been executed. The approval is a starting line, not a finish line.
Why one road determines the whole southern corridor
There is a distinction worth drawing carefully here. King 31 is not stranded without any road connection: the A1 roundabout junction that will serve the site was built as part of Phase 2 of the Grantham Southern Relief Road (GSRR) and is already in place. Vehicles can, in principle, reach the site from the A1. That is a meaningful difference from a development with no access infrastructure at all.
The constraint is elsewhere — and it operates at a corridor level, not a site level.
Phase 3 of the GSRR is the 3.5-kilometre link that crosses the Witham Valley, spanning both the River Witham and the East Coast Main Line on a 293-metre steel bridge. Until that section opens, the southern Grantham network lacks the capacity to absorb the combined traffic generated by the developments already consented in the area. Traffic modelling prepared for the planning process shows that without the full GSRR alignment, existing roads south of the town would face gridlock as cumulative permissions are built out. The problem is not King 31 in isolation; it is what happens when King 31 is added to everything else.
Spitalgate Heath Garden Village makes this plain. The allocation, on the southern fringe of Grantham, provides for between 3,500 and 3,700 new homes alongside up to 120,000 square metres of employment floorspace. It too depends on Phase 3 for its traffic model to hold. The planning system anticipated this mutual dependency: the South Kesteven Local Plan requires southern Grantham developments to contribute to GSRR delivery, while the road itself is partly funded through those same developer contributions. Phase 3 is not one project's problem — it is the load-bearing piece of the whole southern corridor.
Two engineering failures behind the bridge delay
Two separate engineering failures, three years apart, account for where the project stands today.
The first emerged in July 2022, during foundation work for the Witham Valley crossing. Geotechnical surveys revealed soft, unstable ground beneath the planned bridge piers — ground that could not bear the loads the original design assumed. The solution required longer, heavier piers, adding complexity and cost before a single metre of the deck had been assembled.
The second failure was discovered in February 2025, and it was of a different character entirely: not a geological surprise but a design process error. Engineers had not accounted for wind loading during the incremental bridge-push operation — the method by which the completed deck sections would be slid, piece by piece, across the East Coast Main Line and the River Witham. The concern was straightforward in retrospect: as wind acts laterally on a partially advanced deck weighing approximately 2,500 tonnes, it can cause the structure to flex and drift out of alignment during the push. The design had not modelled for this. The operation had to be redesigned before it could begin.
Together, the two failures have added roughly two years to the project schedule and between £10m and £20m to the cost — taking the total from a base figure of £148m to as much as £168m. Lincolnshire County Council has stated it intends to recover the additional expenditure from the parties responsible for the design errors, a signal that the overrun has not been quietly absorbed.
The bridge push itself began in early 2026. It is a slow, meticulous operation — the deck advances incrementally, with progress measured in millimetres per minute, on temporary supports. The June 2026 LCC update described the installation of 60.5-metre supports to Piers 2 and 3, with a planned advance to Pier 2 scheduled for summer 2026. When the push began, the council estimated the road remained approximately two years from full opening — placing completion somewhere in 2027 or 2028, contingent on the push proceeding without further complications.
The funding loop that ties developers and the road together
What section two sketched as a mutual dependency has a specific mechanism behind it: developer contributions — secured through Section 106 agreements and the Community Infrastructure Levy — are committed at planning approval but flow in stages as construction proceeds. The GSRR's funding structure relied on those contributions sitting alongside grants from the Local Transport Board (£11.9m), the Single Local Growth Fund (£16.1m), and Highways England's Growth and Housing Fund (£5m), all forward-funded by Lincolnshire County Council on the assumption that development in southern Grantham would materialise in step with the road.
When the road slips, that assumption gets tested. Sites that have not broken ground generate no contributions. King 31's outline consent, granted in March 2026 but still conditional on a Section 106 agreement not yet signed, sits in exactly this position: the legal instrument that would lock in the financial commitment remains unexecuted. Until reserved matters are approved, groundworks start, and the agreement completes, the contribution is unrealised. The sequencing delay is simultaneously a funding-flow delay — the road waits, in part, on money that the road's own delay is helping to withhold.
The planning conditions attached to the outline consent also make clear that tarmac is only one element of what must converge. Anglian Water's objection over sewerage network capacity and Active Travel England's concerns about walking and cycling provision are both live conditions that the reserved matters process and Section 106 negotiations must resolve before any occupier can move in. They are not marginal notes: they are structural requirements sitting inside the same planning consent as everything else. The job numbers projected for King 31 depend on drainage infrastructure, active travel connections, and road access all arriving together — not on any single element in isolation.
From outline permission to first job: what the gap actually looks like
The two job-creation figures in circulation for King 31 measure different things, and understanding which is which matters when assessing what the site can actually deliver.
The figure of approximately 2,200 full-time equivalent jobs was presented to South Kesteven's planning committee in March 2026 and reflects King 31 at full build-out — all 140,000 sq m occupied and operational. The Greater Lincolnshire LEP's figure of 370+ jobs is scoped more narrowly: it represents employment forecast to be generated or safeguarded in direct relation to the GSRR-enabled access phase of the wider corridor. Neither number is wrong; they are measuring different points on a long delivery curve. Conflating them would simultaneously overstate near-term impact and undervalue the site's eventual scale.
What neither figure addresses is timing. No public document maps the interval between outline permission and first occupier. The remaining stages — Section 106 execution, reserved matters approval, discharge of conditions (including drainage capacity and active travel provision), then groundworks, build-out, and occupier fit-out — are normal for a site of this size but are also cumulative. At comparable logistics and industrial allocations in the East Midlands, the gap between outline consent and a first tenant has typically run to three to five years.
The GSRR opening estimate of 2027–2028 sets an outer constraint for the wider corridor, not a starting gun for King 31 in isolation. The site's A1 junction is already in place, but the fuller transport logic that makes southern Grantham viable for large-scale occupiers does not function until Phase 3 is open. Absent a published delivery programme, meaningful employment on the site before 2029 looks unlikely — and the timeline could extend further depending on how quickly reserved matters proceed and how the logistics market responds.
What infrastructure sequencing means for Grantham's job market
Planning approval and economic intent are genuinely distinct things, and King 31 makes that gap visible. The permission exists. The site exists. The road is 90 per cent built. None of that translates directly into a job in southern Grantham.
What fills the gap is the convergence of systems that rarely move at the same pace: a bridge being pushed millimetre by millimetre across the East Coast Main Line, a Section 106 agreement not yet signed, sewerage capacity that Anglian Water has not yet confirmed, and a logistics market that will respond only once the transport logic of the full corridor is operational. Each element is necessary; none is sufficient on its own.
For local workers and businesses, the practical consequence is that southern Grantham's manufacturing and distribution capacity remains constrained until at least 2027–2028, and likely beyond. The GSRR story also illustrates what compounding risk looks like in practice: unstable ground discovered in July 2022, a wind-loading design error surfacing in February 2025, and a cost recovery dispute with designers can each independently shift the timeline without any single party making a catastrophic decision.
The site exists. The permission exists. The road is 90 per cent there. The gap between those facts and a job offer in Grantham is what infrastructure sequencing looks like from the inside — patient, interdependent, and far less predictable than any planning consent date might suggest.