When I set out to visit every postcode district in London this year I hadn't fully grasped the scale of the project. This was partly because no definitive list exists so I had to make my own, and also because I hadn't realised how awkward some of the locations would be.
I started with the London postal district, that's EC, WC, N, E, SE, SW, W and NW, and totted up 120 postcode districts from EC1 to W12. Within six weeks I'd visited all of them, mostly as a consequence of travelling around the capital anyway. So far so straightforward.
Only when I tried enumerating the outer London districts, that's BR, CM, CR, DA, EN, HA, IG, SL, TN, KT, RM, SM, TW, UB and WD, did things become more complicated. Many of these postcode districts overlapped the Greater London boundary, some lay entirely outside and in a few cases it wasn't clear whether they crossed or not. My spreadsheet became a work in progress.
It's important to have rules for a project like this and these were mine.
• I decided not to treat subdistricts as separate, so for example all of SW1A, SW1E, SW1H, SW1P, SW1V, SW1W, SW1X and SW1Y fell under the umbrella of SW1.
• I decided to discount non-geographical postcodes (like CR9 or E77) because life's too short.
• To be included, a postcode district needed to have at least one postal address within Greater London.
• I had to set foot within the postcode district, passing through it didn't count.
• I had to set foot in the London part of the postcode district, outside London didn't count.
And with all that sorted I decided the number of postcode districts in Greater London was somewhere between 230 and 250, depending on full geographical accuracy. I shared a draft version of the following table with you back in February after I'd successfully visited every postcode district in the first two columns. Back then it also had a 'Maybe' column, so I'm pleased now to bring you what I hope is a definitive list.
In summary, 190 postcode districts are wholly within Greater London, another 24 postcode districts are mostly within Greater London and 29 postcode districts are marginally in Greater London. That's a grand total of 243, i.e. to visit every postcode district in London you have to tick off all 243 of them.
I achieved this feat earlier this week when I finally stepped from CM13 into CM14. I'd visited both of these districts outside London before but never within. I may be the only person ever to have achieved this feat, but we'll see about that.
My Peripheral Postcodes series has focused on the third column, the postcode districts that are more without London than within. I was surprised by how marginal some of them were, as if the Post Office very nearly aligned their districts to administrative boundaries but then let practicalities warp the boundary on the ground. Let's see how tiny.
Six of the 29 overlaps are quite substantial...
UB9: 15km² of northwest London around Harefield TN16: 15km² of almost-Kent around Biggin Hill CR5: 12km² at the southern tip of London around Coulsdon RM4: 7km² of northeast London around Havering-atte-Bower (blogged) TN14: 5km² of almost-Kent including Cudham and Hazelwood DA1: 4km² of Crayford adjacent to Dartford
Size-wise they're the easy ones to get (although four of them are station-less, and RM4 and TN14 don't merit even one bus an hour). For comparison, a typical inner London postcode like E3 covers 5km².
Another 6 overlaps have an area somewhere between 1km² and 2km².
KT8: essentially Hampton Court TW19: West Bedfont and Spout Lane North (nr Heathrow) (blogged) SM7: Oaks Park, Mayfield Lavender and Cuddington (blogged) IG7: Hainault (north of Manford Way) BR8: Hockenden (beyond the Swanley bypass)
KT8 is tourist central so you've probably been there. IG7 is easy to get to on the Central line and SM7's on the London Loop. But TW19 isn't anywhere you'd go accidentally and Hockenden BR8 is such a minor hamlet I'd never been until last year. If you want to see where all these postcode overlaps are, by the way, you can check my lovingly-curated multi-coloured approximately-correct Google map.
The next 9 overlaps have an area between ¼km² and ¾km². They all featured in my Peripheral Postcodes series because one does not visit these undeliberately.
RM15: Belhus Woods Country Park (in should-be-Thurrock) (blogged) WD3: Springwell Lane (nr Mill End, Rickmansworth) (blogged) IG9: a few streets in Buckhurst Hill and Roding Valley (blogged) TW15: Bedfont Lakes Country Park (south) and 3 adjacent streets (blogged) EN6: The Ridgeway, NW Enfield (round New Cottage Farm) (blogged) CR3: Coulsdon Common and Kenley/Whyteleafe (blogged) CR6: One borderline road in Hamsey Green (plus Sheepbarn Lane) (blogged) EN8: Bullsmoor alongside the Holmesdale Tunnel (blogged) CM14: Grove Farm (M25 J28) and one house on Nags Head Lane (blogged)
And finally the titchiest 9 overlaps of all. We're talking 10 hectares (25 acres) or less.
CM13: Warley Road and Tylers Wood (by the M25 nr Brentwood) (blogged) KT18: two farms on Rushett Lane (Malden Rushett) (blogged) EN7: Capel Cottage and Bulls Cross Lodge (near M25 J25) (blogged) KT17: Sparrow Farm Road and Richlands Avenue (Stoneleigh) (blogged) EN9: Rammey Marsh on the river Lea (Waltham Cross) (blogged) KT19: 16 houses on Chessington Road plus one cul-de-sac (blogged) WD23: Magpie Hall Lane, Bushey Heath (one side only) (blogged) WD6: Elstree Park (mobile homes) Stirling Corner, Borehamwood (blogged) KT22: The Star, Malden Rushett (and a dozen cottages) (blogged)
These are the lowliest postcode districts in Greater London, tiny enclaves with a handful of properties, in some cases just two addresses a postal worker might visit. KT22 may be the tiniest of all, just a pub and a row of cottages which by all rights should be in Surrey but somehow isn't. Such are the quirks when administrative boundaries are overlaid on a system designed to optimise postal delivery.
And this is why I don't think anyone else has been to all 243 postcode districts. You'd have to have walked down one particular pavementless road on the edge of Havering, crossed the bridge at a lock on the Lea Navigation, stopped at a pub in Maldon Rushett, strayed onto a mobile home park off the A1, stumbled upon a cul-de-sac near Chessington AND explored the street south of Cuddington Recreation Ground, PLUS all of the above unlikelinesses. You might have done some of these, but the chances of doing all of them is infinitesimal. [map]
The only way I can think of accidentally ticking these off is if you'd deliberately walked the entire boundary of Greater London, and even then I think you'd have missed a few because they'd not be part of any practical route. Visiting all the postcode districts in Greater London is something you do deliberately or not at all.
...and this is where I invite you to tell me I haven't. It remains possible I've missed a postcode district that dribbles into central London even after six months of on-and-off research. For example I still have a nagging fear that KT7, KT10, KT21 or TW16 might marginally stray across the border. Also Wikipedia seems sure that the SL postcode area (Slough) enters Greater London but I couldn't find any addresses to confirm this. Also the excellent postcode map on london.gov.uk includes five postcode districts that aren't on my list, namely IG10, RM19, SL0, SL3 and WD19. It may be that these only cover open land, not anywhere with a letterbox, in which case I'm saying they don't count. But if you can locate a Greater London address with an IG10, KT7, KT10, KT21, RM19, SL0, SL3, TW16 or WD19 postcode then I haven't finished and I'm going to have to go out and make another visit.
It's over to you. Either I have now visited every postcode district in London or you're going to tell me I'm wrong.