Saturday, April 13, 2024
It's a lovely day in the capital so I hope you're out enjoying the unseasonable warmth rather than wasting your time reading today's post. That's because it's about journeys through consecutively numbered postcode districts, an issue of no practical use whatsoever.
Here's an approximate schematic of the postcode districts in central London.
WC1 and WC2 cover the West End and EC1-EC4 are essentially the City.
WC: The dividing line between WC1 and WC2 roughly follows the alignment of New Oxford Street and High Holborn. To walk from WC1 to WC2 is as simple as crossing the road outside Holborn station.
EC: The triple point between EC1, EC2 and EC4 is just outside St Paul's station. To walk the EC postcode districts consecutively simply walk from there along Cheapside and then do a circuit of Bank junction, which is the EC2, EC3 and EC4 triple point.
It's quick and easy to walk the districts of WC and EC consecutively. As a spoiler, these are the only London postcode areas you can walk consecutively, so you can stop reading here.
Things get more awkward in W, NW, N, E, SE and SW, the "compass point" districts of the London postal district. That's because they were numbered alphabetically rather than geographically, so the chances of consecutive numbered districts being adjacent is quite low.
Take the E postcode area, for example.
E1, E2 and E3 are next to each other, that's Whitechapel (the Head Office), then Bethnal Green, then Bow. But E4 is Chingford which is nowhere near and so the sequence collapses.
The longest E sequence is five districts long.
E: E8 Hackney → E9 Homerton → E10 Leyton → E11 Leytonstone → E12 Manor Park
It goes wrong either side because E7 Forest Gate isn't near E8 and E13 Plaistow doesn't quite touch E12. As a spoiler 'five' is the maximum chain length anywhere in the London postcode district, so you can stop reading here.
W: W9 Maida Hill → W10 North Kensington → W11 Notting Hill → W12 Shepherds Bush (4)
NW: NW2 Cricklewood → NW3 Hampstead and NW9 The Hyde → NW10 Willesden (2)
N: N10 Muswell Hill → N11 New Southgate → N12 North Finchley (3)
SE: SE21 Dulwich → SE22 East Dulwich → SE23 Forest Hill (3)
SW: SW16 Streatham → SW17 Tooting → SW18 Wandsworth → SW19 Wimbledon → SW20 West Wimbledon (5)
The NW postcode area is particularly rubbish for consecutive adjacent areas. The SW postcode area manages another chain of 5, but that's still not very good.
Things pick up again in the postcode areas covering outer London. Here's RM for Romford.
RM: RM1 Romford → RM2 Gidea Park → RM3 Harold Wood → RM4 Havering-atte-Bower → RM5 Collier Row → RM6 Chadwell Heath → RM7 Rush Green → RM8 Becontree Heath → RM9 Becontree → RM10 Dagenham
It all goes wrong here because RM11 Hornchurch isn't near RM10. That's a shame because what follows is a perfect run from RM11 to RM18 Tilbury, although we've gone outside London by this point. That said, RM1 to RM10 is actually the longest consecutive sequence anywhere in London, so you can stop reading here.
IG: IG4 Redbridge → IG7 Chigwell (4)
EN: EN4 New Barnet → EN5 Barnet (2)
HA: HA0 Harrow → HA3 Harrow Weald (4)
UB: UB1 Southall → UB6 Greenford (6)
TW: TW1 Twickenham → TW6 Heathrow (6)
KT: KT1 Kingston → KT6 Surbiton (6)
SM: SM1 Sutton → SM6 Wallington (6)
CR: CR0 Croydon (1)
BR: BR1 Bromley → BR4 West Wickham (4)
DA: DA5 Bexley → DA8 Erith (4)
I told you RM was long - none of the other postcode areas in London get past six. Also CR is particularly rubbish because none of its nine districts adjoin consecutively anywhere.
If we allow sequences of London postcode districts that go beyond London we can do much better.
IG: IG4 Redbridge → IG10 Loughton (7)
EN: EN4 New Barnet → EN11 Hoddesdon (8)
TW: TW7 Isleworth → TW20 Egham (14)
KT: KT1 Kingston → KT8 East Molesey (8)
This is because most provincial postcode districts are numbered geographically rather than alphabetically. TW is particularly impressive, suggesting that whoever numbered the districts had a consecutive sequence in mind. Only the leap from TW6 Heathrow to TW7 Isleworth breaks the chain. That said, TW7 to TW20 is easily the longest consecutive sequence of postcode districts starting anywhere in London, so you can stop reading here.
But if we ignore the letters and just look at the numbers, we can do 20.
That's the UB sequence from UB1 to UB6, a cunning W7 link through Hanwell and then TW8 all the way to TW20.
UB1 Southall North → UB2 Southall South → UB3 Hayes → UB4 Yeading → UB5 Northolt → UB6 Greenford → W7 Hanwell → TW8 Brentford → TW9 Richmond → TW10 Petersham → TW11 Teddington → TW12 Hampton → TW13 Feltham South → TW14 Feltham North → TW15 Ashford → TW16 Sunbury → TW17 Shepperton → TW18 Staines → TW19 Stanwell → TW20 Egham
This is a long spiralling chain and cannot be beaten. If you have nothing better to do this weekend you could try to follow it from Southall to Egham. The 195 bus from Southall to Hayes ticks off the first four quite nicely, and the 285 from Teddington to Feltham does a nice job of TW11 to TW14. But hopefully you stopped reading a long time ago because it's a lovely day and you're out enjoying the unseasonable warmth.
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