Architecture20/20
Bespoke contemporary residence · named architect to verify
Aveno permanent dossier · published 24 Aug 2026
Harmer Green Lane
Welwyn, Hertfordshire
Aveno evidence graphic · not a photographHarmer Green Lane / evidence-led
Large-scale contemporary leisure house · Welwyn
- Guide
- £3.9m
- Area
- 8,803 sq ft
- Identity
- 84 / 100
- Data
- 88 / 100
Independent reading
An 8,803 sq ft gated contemporary residence with an indoor pool, gym, seven-bedroom main house, guest annexe and triple garaging in 1.45 private acres.
The scale, leisure architecture, privacy and entertaining programme clear the Pavello benchmark. The reduced £3.85m guide equates to about £437/sq ft using the agent's 8,803 sq ft main figure, but current portal headers also expose a range up to 9,691 sq ft. The legal identity, component areas, pool/plant condition and exact scope of the annexe must be reconciled before the apparent density is treated as value.
Remarkability99/100
Data readiness88/100
Ownership intensityHigh
Why this belongs in Aveno
Remarkable is
an evidence test.
Flagship intelligence99remarkability / 100
Admitted to Aveno on architecture, live market evidence, defensible identity and structured buyer intelligence; no film is presented until an exact-property source is verified.
Luxury and finish20/20
Premium specification and lifestyle scale.
Privacy and setting19/20
Detached and materially private; legal boundaries remain to verify.
Visual quality12/20
No film displayed pending an exact-property verification.
Market distinction20/20
Price, rarity and accommodation support admission.
Data-readiness audit · 88/100
Exact identity17/20
Harmer Green Lane, Welwyn; official UPRN/title bridge remains buyer-side.
Market status20/20
Live primary or syndication listing checked 24 Aug 2026.
Price and area18/20
£437/sq ft from current guide and publisher area.
Buyer intelligence17/20
Costs, title, planning, energy, environmental and comparable questions are structured.
Rights and media20/20
No unverified third-party visual is displayed; Aveno evidence graphics and the live source remain available.
- An 8,803 sq ft gated contemporary residence with an indoor pool, gym, seven-bedroom main house, guest annexe and triple garaging in 1.45 private acres.
- 8,803 sq ft at £3.9m clears Aveno's luxury threshold.
- The dossier prioritises verified evidence over an unconfirmed visual.
- Live listing and current guide
- Price-density and component cost model
- Transaction and comparable caveats kept explicit
- Official house name/number, title number, UPRN and registered extent
- Signed component-area schedule explaining the 8,803–9,691 sq ft range
- Current EPC certificate, planning/completion/warranty archive and actual pool, energy, security, grounds and insurance costs
Aveno Decision Engine · live model
What does the evidence
change?
Current buyer actionVIEW — VERIFY THE DECISION PACK
The scale, leisure architecture, privacy and entertaining programme clear the Pavello benchmark. The reduced £3.85m guide equates to about £437/sq ft using the agent's 8,803 sq ft main figure, but current portal headers also expose a range up to 9,691 sq ft. The legal identity, component areas, pool/plant condition and exact scope of the annexe must be reconciled before the apparent density is treated as value.
Identity confidence84%
Harmer Green Lane, Welwyn
The live OnTheMarket instruction and current Rightmove and Zoopla syndications carry the same Savills Harpenden fingerprint: Harmer Green Lane, the AL6 area, a reduced £3.85m asking position, seven bedrooms, six bathrooms, 8,803 sq ft, about 1.45 acres, freehold tenure, EPC C and the same pool, gym, annexe and triple-garage programme. A historic Savills distribution record narrows the postcode to AL6 0AP, but the public marketing withholds a house number/name and the official title/UPRN bridge remains buyer-side. Confidence is therefore deliberately capped at 84 rather than presenting the editorial street identity as a legal address.
UPRNStill protected
01
Premium test
Is the asking premium supported?
Guide midpoint£3,850,000£4,708 / m²
versusLocal evidence benchmarkWithheld0 size-known local references
Subject vs unadjusted evidence—
ReferenceDateAreaPrice / ask£/m²
Resulting referenceWithheldNot a valuation. It exposes how much premium the evidence must justify.
The references are not a surveyor-selected valuation set. Recency, condition, land, architecture and improvements are not fully adjusted. Aveno shows the gap instead of hiding it behind false precision.
02
True ownership load
The cost after the keys.
Five-year cost above purchase price£812,250–£1,377,750SDLT + disclosed transaction extras + acquisition checks + modelled running and replacement allowances. Mortgage interest and major defects excluded.
Council taxCurrent listing band; exact authority charge and any annexe assessment to verify.£3,500–£6,000attributed
Energy, water and private systemsScale, plant, pool/estate systems and attributed energy setup; bills missing.£16,400–£47,500modelled
Insurance and securityHigh-value rebuild, gates, glazing, outbuildings and setting.£9,840–£28,500modelled
Building, plant and interior reserveComponent-based reserve for envelope, glazing, smart controls, kitchens, bathrooms and mechanical plant.£32,800–£66,500modelled
Grounds, access and lifestyle amenitiesLandscaping, woodland/land, pool/equestrian/garaging where applicable and access upkeep.£22,960–£47,500modelled
03
Claim audit
Marketing claim → buyer consequence.
Evidence readiness88/100
Tap the evidence cards as if the seller supplied them. Aveno recalculates the decision—not the beauty.
PROCEED TO VALUATION04
Property memory
The home’s price story.
Direct transaction memory is not yet matched.
This history does not prove fair value. It tells the buyer exactly how much of the current price must be explained by market growth, improvements, specification and scarcity.
Official evidence map
What is matched.
What is withheld.
Land Registry can establish sale history; EPC can reveal rated floor area and energy assumptions; Planning Data can surface constraints by UPRN or coordinate. A link alone is never counted as intelligence.
connected
Live exact-property instruction supplied by Savills Harpenden: reduced £3
Live exact-property instruction supplied by Savills Harpenden: reduced £3.85m ask, detached type, 8,803 sq ft, seven bedrooms, six bathrooms, freehold tenure, EPC C, Band H, 1.45 acres, specification and working enquiry route.
Source ↗connectedCurrent cross-market listing confirms the 14 July 2026 reduction, £3
Current cross-market listing confirms the 14 July 2026 reduction, £3.85m position, Savills instruction, 8,803–9,691 sq ft range and matching accommodation and leisure fingerprint.
Source ↗connectedCurrent Savills syndication confirms the reduced £3
Current Savills syndication confirms the reduced £3.85m position, freehold tenure, EPC C and exact matching property programme.
Source ↗connectedOpen Postcode-derived AL6 0AP centroid used only for an area-precision map marker; it is not represented as a parcel or front-door coordinate
Open Postcode-derived AL6 0AP centroid used only for an area-precision map marker; it is not represented as a parcel or front-door coordinate.
Source ↗not matchedOfficial planning and Building Control search route; an exact application and completion bridge requires the withheld legal house identity
Official planning and Building Control search route; an exact application and completion bridge requires the withheld legal house identity.
Source ↗not matchedProperty-level river, surface-water, groundwater, drainage and climate-risk evidence remains required
Property-level river, surface-water, groundwater, drainage and climate-risk evidence remains required.
Source ↗Published / verified
- The live Savills-supplied instruction shows an offers-in-region-of £3.85m position, seven bedrooms, six bathrooms, 8,803 sq ft, freehold tenure, EPC C, Council Tax Band H and approximately 1.45 acres.
- The four-storey accommodation includes a marble entrance hall and 360-degree galleried landing, principal and guest suites with dressing rooms, five further bedrooms, several reception rooms and a south-westerly garden connection.
- The lower-ground leisure suite combines a heated indoor pool, jacuzzi, changing/shower room, gym and plant room; a detached triple garage carries a self-contained annexe above.
- The listing attributes gated access, a circular drive, CCTV, a monitored alarm and a boosted whole-house Wi-Fi network.
Investigate next
- Obtain the official title register/plan, UPRN and postal identity, then reconcile the private marketing address, AL6 0AP postcode, 1.45-acre extent, access, covenants and boundaries.
- Commission a RICS component measurement reconciling the 8,803 sq ft main figure and current 8,803–9,691 sq ft portal range, explicitly separating house, pool/leisure level, garage and annexe.
- Retrieve the complete planning and Building Control archive, warranties and professional appointments, then survey structure, roofs, glazing, terraces, pool shell and plant, jacuzzi, heating, electrics, security, drainage and annexe; obtain three years of utility and maintenance records.
Still unknown
- Official house name/number, title number, UPRN and registered extent
- Signed component-area schedule explaining the 8,803–9,691 sq ft range
- Current EPC certificate, planning/completion/warranty archive and actual pool, energy, security, grounds and insurance costs
Primary publisher · visual-rights recordSavills Harpenden via OnTheMarketOpen original source ↗Open rights-basis evidence ↗
No third-party property film or photography is displayed. Use the prominent live market source for real-property media; Aveno shows only its original evidence graphics. No exact-property film is displayed. The dossier uses only Aveno's original evidence presentation and links to the live market source; no estate-agent media is copied, downloaded, screenshot, rehosted or hotlinked. Aveno original evidence panel; no third-party property media is reproduced or embedded. Third-party material remains the property of its publisher. The publisher does not endorse Aveno’s independent assessment.
Durable archive record
Versioned evidence.
Every claim traceable.
Record 1.0-private · admission policy 2026-08-luxury. Facts, attributed claims, estimates and gaps remain separate.