Which Islington postcodes does this basement extension service cover?
Every Islington postcode district we draw in, the stock that dominates
it and the authority that validates a basement extension there. Islington fees below are the
statutory England rates for 2026, not basement extension estimates.
| Postcode | Area | Dominant stock | What it means for a basement extension |
|---|
| N19 | Archway / Tufnell Park | Victorian terraces, post-war flats | A basement extension in Archway / Tufnell Park may land with Islington Council or Camden Council — N19 crosses the boundary, and the N19 policies map decides it street by street. |
| EC1M | Clerkenwell | Georgian and early Victorian terraces | EC1M covers Clerkenwell only; Islington Council handles the basement extension. |
| EC1R | Clerkenwell / Exmouth Market | Georgian and early Victorian terraces | Clerkenwell / Exmouth Market sits wholly inside EC1R, so Islington Council validates every basement extension submitted from an EC1R address. |
| EC1V | City Road / Old Street | Georgian and early Victorian terraces | EC1V covers City Road / Old Street only; Islington Council handles the basement extension. |
| EC1Y | Bunhill / Whitecross | Georgian and early Victorian terraces | EC1Y covers Bunhill / Whitecross only; Islington Council handles the basement extension. |
| N4 | Finsbury Park / Stroud Green | Victorian terraces, post-war estates | Finsbury Park / Stroud Green is split at N4. Either Haringey Council or Islington Council or Hackney Council can determine a basement extension here, so the N4 address is checked against both policies maps first. |
| N16 | Stoke Newington / Stamford Hill | Georgian and Victorian terraces | N16 straddles a boundary: Stoke Newington / Stamford Hill addresses fall to Hackney Council or Islington Council, so confirm which authority validates the basement extension before submitting N16 drawings. |
| WC1X | Bloomsbury / Mount Pleasant | Georgian and early Victorian terraces | Bloomsbury / Mount Pleasant is split at WC1X. Either Camden Council or Islington Council can determine a basement extension here, so the WC1X address is checked against both policies maps first. |
Which Islington neighbourhoods suit a basement extension best?
Roof pitch, wall build-up and plot depth change every few Islington
streets, and each one changes what a basement extension can achieve at that address.
- Tufnell Park (N7, N19) — basement extension work in Tufnell Park means victorian villas and terraces. Tufnell Park is Victorian villas and terraces. Victorian cellars here convert without planning permission when the footprint and external appearance are unchanged throughout N7. Islington Council decides the Tufnell Park application, and Tufnell Park station anchors the Tufnell Park location plan.
- Holloway (N7) — basement extension work in Holloway means victorian terraces, post-war estates. Holloway is Victorian terraces, post-war estates. Victorian cellars here convert without planning permission when the footprint and external appearance are unchanged throughout N7. Islington Council decides the Holloway application, and Holloway Road anchors the Holloway location plan.
- Newington Green (N16) — a basement extension in Newington Green starts from georgian and victorian terraces, and Newington Green reads as Georgian fragments, Victorian terraces. Georgian houses here already have a vault and a lower-ground floor in N16. Islington Council assesses Newington Green basement extensions against its own Newington Green character guidance, and the location plan we draw for Newington Green references Newington Green.
- Angel (N1, EC1V) — basement extension work in Angel means georgian and early victorian terraces. Angel is Georgian terraces, dense town centre. Georgian houses here already have a vault and a lower-ground floor throughout N1. Islington Council decides the Angel application, and Angel station anchors the Angel location plan.
- Barnsbury (N1) — Georgian conservation area defines Barnsbury, where georgian and early victorian terraces set what a basement extension can do. Georgian houses here already have a vault and a lower-ground floor across N1. Any Barnsbury basement extension is validated by Islington Council, with Barnsbury Square the usual Barnsbury reference point on the site plan.
- Canonbury (N1) — Georgian and Victorian conservation area defines Canonbury, where georgian villas, victorian terraces set what a basement extension can do. Georgian houses here already have a vault and a lower-ground floor across N1. Any Canonbury basement extension is validated by Islington Council, with Canonbury Square the usual Canonbury reference point on the site plan.
- Highbury (N5) — basement extension work in Highbury means victorian terraces, mansion blocks. Highbury is Victorian terraces around Highbury Fields. Victorian cellars here convert without planning permission when the footprint and external appearance are unchanged throughout N5. Islington Council decides the Highbury application, and Highbury Fields anchors the Highbury location plan.
Does Islington planning policy restrict a basement extension?
Islington conservation designations: there are 40 across Islington Council, Clerkenwell, Angel, Barnsbury among them. Designation costs a Islington owner the permitted-development route: a basement extension then needs a £548 householder application over 8 weeks, in place of the £249 prior approval route that takes 6 weeks. Clerkenwell is the Islington designation that most often changes a basement extension design.
What Article 4 removes near Islington: Article 4 Direction covering the whole borough removes permitted development rights for HMO conversions (C3 to C4). Separate Article 4 for office-to-residential in key areas. Before pricing a basement extension we check whether the N1 address is inside the mapped area, because Islington Council draws the Islington boundary street by street rather than across the whole of Islington.
Islington housing stock: Georgian and early Victorian terraces, Victorian bye-law housing, 1930s mansion blocks, converted industrial buildings in Clerkenwell and Farringdon. Densely terraced, gentrified; strong conservation area coverage; active planning department. Read that before choosing a basement extension route in Islington — construction, not postcode, sets what is achievable.
What happens if a Islington property sits on a boundary?
- Camden — cross the Islington boundary and Camden Council takes the basement extension instead, applying 40 conservation areas of its own around NW1. We re-price basement extensions at the Islington edge because Camden policy and Islington policy rarely align on basement extension depth.
- Hackney — cross the Islington boundary and Hackney Council takes the basement extension instead, applying 29 conservation areas of its own around E2. We re-price basement extensions at the Islington edge because Hackney policy and Islington policy rarely align on basement extension depth.
- Haringey — cross the Islington boundary and Haringey Council takes the basement extension instead, applying 29 conservation areas of its own around N4. We re-price basement extensions at the Islington edge because Haringey policy and Islington policy rarely align on basement extension depth.
- City of London — adjoining Islington, with 27 conservation areas centred on EC1. A basement extension on the far side of the Islington line is determined by City of London Corporation, so the Islington quote for basement extensions is checked against City of London guidance before it is issued.
Sources for this Islington basement extension page: borough policies maps and
conservation-area registers (2025–26), Royal Mail postcode district boundaries,
the Town and Country Planning (Fees for Applications) (England) Regulations, the Town
and Country Planning (General Permitted Development) (England) Order 2015 as amended,
and the Party Wall etc. Act 1996.
