City of Westminster · W1J

Plumbing compliance check in W1J (Mayfair – south)? We'll point you the right way.

Covering Mayfair – south, Piccadilly, Royal Academy, including Clerkenwell, St James's, West End. Find plumbers nearby.

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W1J (Mayfair – south) in a nutshell

W1J covers Mayfair – south, Piccadilly, Royal Academy, in Islington and Westminster. Give your full postcode when you ask for quotes, so the pro can confirm they cover your street.

Local tips for W1J

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Two councils in one district

W1J is split between Islington and Westminster. Some councils run their own landlord licensing, so check which one your home is in.

Where's this from?postcodes.io (ONSPD) local authority
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Give your full postcode

W1J stretches across Clerkenwell, St James's, West End, so give your full postcode, not just 'W1J', when you ask for quotes.

Where's this from?postcodes.io (ONSPD) wards
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Converted flats and bedsits

Converted houses often share pipework between flats, so a leak upstairs can become your problem. Know where your stopcock is!

Where's this from?ONS Census 2021, City of Westminster: 16.0% converted/shared houses
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New to plumbing compliance checks? Here's what to expect, how to get ready and what it costs, in plain English. Read the quick guide →

England landlord rules: quick version

  • No single certificate: but keep water, heating and sanitation in repair.
  • Legionella: assess the risk for each let.
  • CO alarms: needed where there's a fixed combustion appliance (not gas cookers).

More detail on the City of Westminster page. Always double-check on GOV.UK.

Next door to W1J

W1S · Hanover SquareW1K · Mayfair – northW1B · Portland StreetW1C · Oxford Street – westSW1Y · St. James's

← Plumbing & water compliance across City of Westminster · all areas

Frequently asked questions

Which areas does W1J cover?

W1J (Mayfair – south, Piccadilly, Royal Academy) includes the wards of Clerkenwell, St James's, West End (ONS Postcode Directory via postcodes.io).

Which postcode districts are next to W1J?

Neighbouring districts include W1S (Hanover Square), W1K (Mayfair – north) (ONS Postcode Directory via Doogal). A pro covering W1J may well cover these too, so it's worth asking.

How many homes are in W1J?

About 820 households and 1,396 residents at the 2011 Census, across 666 active postcodes (Doogal / ONS Postcode Directory).

Which council area is W1J in?

W1J sits in Islington, Westminster (postcodes.io). Parliamentary constituency: Cities of London and Westminster, Islington South and Finsbury.

📊 The numbers behind this page
Postcode district
W1J 1
Areas covered
Mayfair – south, Piccadilly, Royal Academy 2
Active postcodes
666 3
Households (2011 Census, via Doogal)
820 2
Population (2011 Census, via Doogal)
1,396 2
Electoral wards
Clerkenwell, St James's, West End 4
Parliamentary constituencies
Cities of London and Westminster, Islington South and Finsbury 4
Local authority
Islington, Westminster 4
Households in converted/shared houses (City of Westminster built-up area)
16.0% 5
  1. ONS Postcode Directory
  2. Doogal
  3. Doogal / ONSPD
  4. postcodes.io
  5. ONS Census 2021

Made with open data. See where it all comes from. Updated 26 October 2026.