please empty your brain below
What about CR9? It’s a non-geographic postcode, but I suspect most of the buildings are in the London Borough of Croydon. Might be able to let you in one if you are desperate.

Robert Butlin | 15.02.23 - 8:10 a.m. | #

I've omitted non-geographic districts from that list because by definition you can't visit them.

diamond geezer | Homepage | 15.02.23 - 8:11 a.m. | #

Excellent! I'm looking forward to it, I love a bit of edgelands...

Steve | 15.02.23 - 8:11 a.m. | #

Quote: "Where precisely is WC2H anyway?"

It is the Very Centre of the Universe, as I live there. It stretches from the National Gallery, through Leicester Square, to New Oxford Street just west of Tottenham Court Road station. You have been there!

The Banbury Man | Homepage | 15.02.23 - 8:14 a.m. | #

I was relieved to read that you have a "stuff that, life's too short" reflex, but then read on and wonder if you actually do.
Looking forward to the posts about the borderlands.

Frank F | 15.02.23 - 8:34 a.m. | #

If I understand correctly, the trouble with postcode districts is that they don't have boundaries per se. They're just clusters of addresses. So as you suggest, the only way to define "inside/outside London" is to look up postcodes and council tax/LA details for the marginal addresses. Sounds fun though!

David F | 15.02.23 - 8:49 a.m. | #

Is this all based on a misunderstanding? Local authority areas have well defined boundaries, and every point on the surface of Britain is in one of them. But postcodes are not like that. They are finite sets of deliverable addresses. An oak tree in a field, or the mid point of a pedestrian crossing, cannot be assigned to any postcode (unless someone lives there).
However, if it is a misunderstanding, it's still quite a fascinating one.

Malcolm of Kent | 15.02.23 - 8:52 a.m. | #

If the GLA can produce a map of postcode districts and local authorities can add postcode districts to street signs then postcode districts definitely exist.

The chief issue is their boundaries which can be woolly and ill-defined.

diamond geezer | Homepage | 15.02.23 - 8:56 a.m. | #

Some of the Ordnance Survey street atlases show postcode areas. I have such atlases for London and for South Essex and these both show the postcode boundaries down to street level.

Alan S | 15.02.23 - 9:09 a.m. | #

IG10 doesn't seem to have any addresses within waltham forest (or redbridge) the closest candidate is the Conaught water car park and it seems to be an E4 despite being in the IG10 area.

dg writes: shifted, thanks.

Alistair Twin | 15.02.23 - 9:10 a.m. | #

That nugget of postal delight made me look up what the letters WC and EC actually stand for. I'd assumed, incorrectly, that it might be West City and East City. But no, it's West Central and East Central. Which in turn prompts the question: Where's Central, and what defines the 'border' between W and E? A look at maps online indicates nothing as simple as a straight line for a border, or even sticking to main roads. I'm thinking you'll have covered this in the past, but perhaps a 2023 walk along the border is required.

dg writes: been there done that.

Stuart writes: 2016. No wonder I hadn't seen it! Nicely done.

Stuart R | 15.02.23 - 9:19 a.m. | #

I had a spell working with mailing data and was amazed to learn the number of post code changes that occur.

The ONS Open Geography Portal is the source of much of the boundary data other websites use. Here you'll find a postcode post code look up tool. Census data allocations to geographic boundaries is a genuine postcode challenge. The ONS approach is to 'take the grid reference of the postcode centroid and match this up to digital administrative boundaries. However, some addresses (and therefore data) will still inevitably be allocated to the "other" area'.

Rod | 15.02.23 - 9:32 a.m. | #

I've always wondered what sort of directory is behind those web tools which purport to tell you what parliamentary constituency, or local authority ward, you live in, based just on your postcode.
Postcodes were designed in the 1960s just as a mail-sorting tool, without any plan to link them to administrative boundaries. Identifying a constituency or ward by postcode must be a software writer's nightmare.

Alan BG | 15.02.23 - 9:54 a.m. | #

The centroid of a postcode region strikes me as a flaky concept. Either it is the arithmetic mean of all the points in the region, which assumes that the region has firm boundaries, or it's the mean of all the addresses in the region, which would mean that it could be shifted by someone splitting a house into multiple flats.

Malcolm of Kent | 15.02.23 - 9:54 a.m. | #

What the hell is going on with DA8 down river in that postcode/GLA map? It looks as though there's an unidentified no-man's-land taking a chunk out of it. Is this an estuarine part of London where the mail is delivered -- to passing boats -- by some unknown authority?

Alan BG | 15.02.23 - 9:55 a.m. | #

If you can visit a building with a CR9 postcode then isn't there a teeny bit of an argument that the postcode can be visited, so long as one goes inside the building?

dg writes: as I said, life’s too short.

Robert Butlin | 15.02.23 - 10:01 a.m. | #

I used to produce software for deliveries (of aggregates) and was sometimes approached by salesmen offering postcode maps and databases. It was difficult to convince them that we often delivered to places which did not have postcodes such as building sites, rural road works, railways etc.

Kev | 15.02.23 - 10:54 a.m. | #

Alan, I am almost sure that I have been registered to vote in the wrong ward in the past. The maps produced by my council clearly show the building I was living in is in ward A, but it shared the postcode with a long adjacent street in ward B. I was apparently registered to vote in ward B (I suspect the postcode!) - but it was all a bit academic since there were no elections in the short period of time I lived there.

Jan | 15.02.23 - 11:00 a.m. | #

Stuart R - Almost all the City is in EC. Only the Chancery Lane area, which was added tio the City fairly recently, is WC

timbo | 15.02.23 - 11:53 a.m. | #

Some of the City is also in E1.

Charlie | 15.02.23 - 2:06 p.m. | #

Good luck with this project. Plenty to explore here.

Further to Alistair Twin's comment re IG10 postcode, I googled it and it said it includes Theydon Bois. Streetcheck suggests there are no Theydon Bois streets in IG10; there is one in RM4 towards Abridge. Is Theydon Bois IG10 somewhere deep in Epping Forest?

dg writes: Google also describes Theydon Bois as a city, so perhaps don't be surprised when it gets the postcode coverage wrong.

Richard | 15.02.23 - 2:56 p.m. | #

My parents used to live in IG10, and the one thing I never understood was where the I and the G came from. IG1 is Ilford, so I assume the I is Ilford, but... there's no G in Ilford, and no obvious candidate for an "Ilford and G...". So why G? Years of addressing mail order has left me thinking this is the only inexplicable postcode in the whole of the UK – even SP for Salisbury makes sense once you remember the Plain.

Matt | Homepage | 15.02.23 - 5:17 p.m. | #

IG. I have read on Wikipedia that it is "Ilford and barkinG". Seems as plausible as any other explanation.

timbo | 15.02.23 - 5:36 p.m. | #

Wikipedia's explanation for IG is here.

ChrisL | 15.02.23 - 5:37 p.m. | #

I will not be visiting IG10 because it's not in London. I do regret accidentally placing it in the wrong box.

diamond geezer | Homepage | 15.02.23 - 5:39 p.m. | #

Mmm... so here in UB9 I am only partly in London. I wonder if Sadiq will only partly charge me for ULEZ in August.

Cottonsocks | 15.02.23 - 6:23 p.m. | #

The Banbury Man, that tickled me. Henceforth I shall think of it as Trantor.

Gladys | 15.02.23 - 7:30 p.m. | #

I don't think any of KT7 Thames Ditton is in Greater London. Certainly some streets north of Bullsmoor Lane, Waltham Cross EN8 are in the London Borough of Enfield.

felix | 15.02.23 - 9:57 p.m. | #

Try explaining to people that you live in London, but the postcode is KT2 and your address finishes with Surrey!

Felix- Thames Ditton KT7 is definitely Surrey not London.

RosemaryT | 16.02.23 - 7:09 a.m. | #

In my pile of rarely used phone directories, I've just found one entitled 'Postcodes, London, E1-E18'. It dates from March 1970, when I presume the old GPO was responsible for both postcodes and telephones.

Alan S | 16.02.23 - 8:58 a.m. | #

Always assumed the London Postal District fell entirely within Greater London but learnt today that the northern end of E4 does not. Strangely intriguing in a similar manner to the small slither of Greater London (North Ockendon) that falls outside the M25

Graham T | 16.02.23 - 11:03 p.m. | #

You mention that the 'extra' postcode districts are sometimes extremely small (certainly true) - but also ask where precisely WC2H is.

WC2H is a poor example, but quite a lot of these sub-districts are geographically well-defined and genuinely helpful, with some interesting social history behind them. In particular, E1W (Wapping), EC2Y (Barbican), and N1C (King's Cross Central) are all additions of snobbery - E1W to avoid Wapping's yuppies having to share a postcode with the unwashed masses of Whitechapel; EC2Y to take the City's flagship Barbican Estate out of deprived Finsbury's EC1 postcode (which it initially shared until the mid-70s); N1C to add an additional layer of prestige on to the regular N1 postcode for the new residents of King's Cross Central's expensive flats.

barbicanman | 17.02.23 - 2:08 a.m. | #

No need to waste your time with CM postcodes. Brentwood is very nice. But it is not part of Greater London, and never will be.

R Chalmers | 22.02.23 - 2:10 p.m. | #

I'll be wasting my time later with two CM postcode areas that do indeed stray into Greater London.

diamond geezer | Homepage | 22.02.23 - 2:17 p.m. | #

This discussion made me wonder if anyone's ever made a Voronoi diagram of postcode areas – that is, every spot in the UK being assigned to the postcode area of its nearest building.

So, for the example of a tree in the middle of a field, it would have a postcode area – it would just belong to the "nearest" one.

It turns out someone already did this, in case anyone else is interested, here.

Rob Miller | Homepage | 03.04.23 - 3:19 p.m. | #











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