Party Wall Surveyor Holborn

Holborn is a useful locality name but an unsafe substitute for a planning-authority check. Properties associated with Holborn can sit within the London Borough of Camden or the City of London. Since 10 August 2026, the Oxford Street Development Corporation is also the local planning authority inside its mapped Mayoral Development Area, which reaches the Tottenham Court Road and St Giles edge of the Holborn Vision area. The statutory Party Wall tests remain the same, but the decision-maker and planning material depend on the exact address.

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Resolve the authority before applying local policy

Start with the full property address. The Greater London Authority’s Planning London Datahub provides a location search and a Planning Authority layer. Check that result against the official OSDC boundary map. This is a better starting point than a postcode district, estate-agent description, Tube-station name or assumption about which side of High Holborn a property occupies.

The distinction is substantive. Camden’s Holborn Vision was adopted on 29 January 2025 as a Supplementary Planning Document to Camden’s adopted 2017 Local Plan. Camden submitted a proposed replacement plan in October 2025, but the examination remained in progress on the publication date, so it had not replaced the 2017 plan.

The Oxford Street Development Corporation became the local planning authority inside its area on 10 August 2026. For land transferred from Camden, it uses Camden’s development plan and supplementary guidance, but OSDC is the decision-maker. The Holborn Vision is not a City of London policy document. The Party Wall surveyor London guide gives the wider route, but the address-level authority check must come first.

Record the result in the brief and keep a screenshot or map reference. If the mapped authority and a planning record appear to conflict, resolve that discrepancy with the councils before presenting either policy set as operative.

On the Camden side, Holborn has adopted place guidance and Policy A5

The adopted Holborn Vision SPD divides its area into seven character areas: Museum Quarter; Red Lion and Queen Squares; Great Queen Street; Lincoln’s Inn and Gray’s Inn; Hatton Garden; Tottenham Court Road Growth Area; and High Holborn, Southampton Row/Kingsway. This is useful planning context, but a character-area label does not itself establish a Party Wall trigger.

Where the address is in Camden, basement proposals must be read against Local Plan Policy A5 and the council’s current basement-development guidance. The ordinary dimensional criteria are cumulative. Among them, a basement should:

comprise no more than one storey;
not be constructed beneath an existing basement;
occupy no more than 50% of each garden within the property;
remain below 1.5 times the footprint of the host building;
extend into a garden no further than 50% of the host-building depth and no further than 50% of the garden depth; and
be set back from neighbouring boundaries where it extends beyond the host footprint.

Policy A5 also requires a Basement Impact Assessment addressing drainage, flooding, groundwater and structural stability. The policy’s numerical limits do not prove that a proposal is acceptable, and the BIA does not tell the adjoining owner whether section 6 applies. The statutory comparison still needs the proposed excavation level, its horizontal distance from the adjoining building or structure and the bottom level of that adjoining foundation.

Camden’s basement Article 4 record says the direction applies across the whole London Borough of Camden and came into force on 1 June 2017. It removes the stated permitted-development route so that basement and lightwell excavation requires planning permission. That is a planning requirement, not a substitute for notice or consent under the 1996 Act. The borough-level context is covered on the page for Party Wall surveyors for Camden properties.

On the City side, test archaeology before assuming an excavation brief is complete

The City Corporation’s Local Plan 2015 page identifies that plan as the adopted strategy. City Plan 2040 had not replaced it on the review date: the examination page scheduled additional hearings for 2 and 3 September 2026. A draft or proposed modification should therefore be labelled with its status rather than presented as adopted policy.

Excavation in the City has an additional evidence question. The Corporation’s archaeology page describes a complex and deep archaeological layer surviving below basements, streets and open spaces. Adopted Policy DM 12.4 requires an archaeological assessment and evaluation where an application involves excavation or groundworks on a site of archaeological potential. The adopted plan treats the whole City as having archaeological potential unless evidence shows that remains have already been lost through deep basements or other groundworks.

An archaeological desk-based assessment, evaluation or written scheme answers a planning and heritage question. It does not establish the bottom of the adjoining foundation and is not one of the plans and sections that section 6 requires with its notice. Keep both evidence sets distinct. The authority page for Party Wall surveyors for City of London properties explains the wider City context.

Conservation-area names also change at the authority line

Camden adopted the Hatton Garden Conservation Area appraisal in September 2017. The City Corporation publishes its own conservation-area directory, including a separate Chancery Lane Character Summary and Management Strategy.

Those examples show why “Holborn conservation area” is not a usable status statement. Check the address on the current authority map, record the actual designation and use that authority’s appraisal. Conservation status can affect the planning treatment of lightwells, railings, façades, trees and visible alterations. It neither creates nor removes rights under sections 1, 2 or 6 of the Party Wall etc. Act 1996.

Use the Act’s descriptions, distances and lead times

The Party Wall surveyor guide explains the statutory roles. For a Holborn scheme, separate the proposed works into the Act’s actual categories:

Section 1: the gateway requires differently owned adjoining lands and a line that is unbuilt or occupied only by a boundary wall that is neither a party fence wall nor an external building wall. Where an owner is about to build on that line, notice must be served at least one month before the intended start. Without consent to build astride the line, the statutory alternative is a wall wholly on the building owner’s land and at that owner’s expense.
Sections 2 and 3: before exercising a section 2 right, the building owner ordinarily serves a party structure notice stating the owner’s name and address, the nature and particulars of the work and the proposed start date at least two months before that date. Section 3(3) provides exceptions where every adjoining owner and occupier consents in writing and for compliance with a dangerous-or-neglected-structure notice. Cutting into, raising, underpinning or rebuilding must be identified by the actual work, not merely by calling the project a refurbishment.
Section 6(1): the building owner must propose excavation, or excavation for and erection of a building or structure, within three metres measured horizontally from part of an adjoining building or structure and any part of the proposed excavation, building or structure within those three metres must extend below the level of the bottom of the adjoining foundations.
Section 6(2): within six metres, the separate condition is whether any part of the proposed excavation, building or structure would meet a plane drawn downwards in the direction of the building owner’s work at 45 degrees to the horizontal. The plane starts from the line formed where a horizontal plane at the bottom of the adjoining foundations intersects the plane of the external face of the adjoining external wall.

Where section 6 applies, notice is served at least one month before excavation. It must be accompanied by plans and sections showing the site and depth of the proposed excavation and, where a building or structure is proposed, its site. The party wall notice guide covers the different notice and response routes.

Planning permission, an SPD assessment, conservation approval or archaeological condition does not serve that notice. Equally, adjoining-owner consent or an award does not grant planning permission or discharge an archaeological condition.

Prepare one address-specific comparison brief

For a Holborn request, assemble:

the complete address and the current mapped planning authority;
the applicable Camden character area or City conservation-area record, if any;
existing and proposed plans showing boundary and shared-structure relationships;
sections with excavation levels, horizontal distances and available adjoining-foundation information;
structural details for cutting-in, raising, underpinning, demolition or rebuilding;
the Camden BIA material or City archaeological material relevant to the address;
notices, plans, delivery evidence and any response already received; and
ownership and leasehold information for the interests that may need to be considered.

Do not convert an unknown foundation depth into an automatic notice conclusion. Mark it as an evidence gap so that any proposed scope explains how it will be assessed. If introductions are available and the administrator records your chosen introduction, compare the stated work, documents, inspections, exclusions and responsibility for later stages before appointing the professional. Post your Holborn Party Wall job.

Sources checked

The planning-authority, plan-status, basement, archaeology and conservation statements were checked against the linked GLA, Camden and City of London material on 24 August 2026. The statutory wording was checked against section 1, section 2, section 3 and section 6 of the Party Wall etc. Act 1996. Recheck the address, mapped authority and policy status when the work is being prepared.