Stations outside Greater London but accessible by Oyster
Zone 4: Grange Hill, Chigwell, Roding Valley Zone 5: Buckhurst Hill; Stoneleigh Zone 6: Loughton, Debden, Theydon Bois, Epping; Moor Park (Z6/7); Elstree & Borehamwood; Thames Ditton, Hampton Court; Ewell West; Ewell East; Banstead, Epsom Downs; Chipstead, Kingswood, Tadworth, Tattenham Corner; Whyteleafe; Whyteleafe South, Caterham; Upper Warlingham Zone 7: Croxley, Watford, Rickmansworth, Chorleywood; Carpenders Park; Theobalds Grove; Waltham Cross Zone 8: Chalfont & Latimer; Bushey, Watford High Street; Cheshunt; Dartford Zone 9: Amersham, Chesham; Brentwood Zone G: Purfleet, Grays, Chafford Hundred, Ockendon Zone W: Watford Junction Also: Shenfield; Broxbourne, Rye House, St Margarets, Ware, Hertford East; Merstham, Redhill, Earlswood, Salfords, Horley, Gatwick Airport
• You can see all these zones on the new London rail and tube services map.
• Zones 5 and 6 were originally intended to cover outer London, but three stations beyond the border sneak into Zone 4! They're all on the rim of the Hainault Loop, which was rezoned in 2007 to try to boost passenger numbers.
• The rest of the outer Central line lies entirely in zones 5 and 6, even though it's not in London (in Epping's case not even close).
• More than a dozen stations just outside southwest London form a thin layer of Zone 6.
• Zones 7, 8 and 9 used to be exclusively for the far end of the Metropolitan line, then the Overground joined in, last year Brentwood joined zone 9, and this month Dartford has joined zone 8.
• However zones 7 to 9 have proved too inflexible to cover all the new arrivals, hence four c2c stations near Lakeside were placed in a new 'zone G' in 2010, and Watford Junction became the sole member of 'zone W' at the same time.
• The most recent converts to Oyster don't really have zones in any practical sense. Specifically the Hertford East branch was a fresh addition to Oyster three months back, and the line to Gatwick Airport was added only this week.
• Greater London's transport tentacles now stretch well over ten miles outside the capital - it's either insane or it's the future.
• London's zonal structure conceals a shedload of fare inconsistencies. Sheesh this is complicated.
• See how the two zone 5 stations have different fares? That's because travel by tube is historically cheaper than travel by rail.
• See how tube commuters in zone 7 (eg Rickmansworth) pay less than rail commuters in zone 6 (eg Hampton Court)? Similarly rail travel from Dartford (zone 8) is more expensive than tube travel from Amersham (zone 9). How counter-intuitive is that?
• See how commuters from Chigwell pay less than half as much as commuters travelling from Watford Junction.
• See how commuters from Watford Junction could save two pounds by travelling from Watford High Street, less than a mile away (because that's how much fast trains increase the fare you pay).
• See how fares at the far end of TfL Rail hike up considerably over the last three stations (Harold Wood £5.10, Brentwood £7.60, Shenfield £8.90)
• And see how the most expensive Oyster single fares are on the newly-added line to Gatwick, rising to a massive £14 for an airport trip, and almost £20 if you're stupid enough to use the Gatwick Express.
* If I've got any of this table wrong, it's because TfL no longer publish a list of single fares, they expect you to work it all out by entering station names in their Single Fare Finder. In TfL's defence, the table of single fares has got bloody complicated, as the list above confirms. But if customers don't use the Single Fare Finder properly, it serves up wholly incorrect results. For example Redhill to Victoria comes up as £12.50 (if you pick Victoria tube station), whereas the correct fare is really £10.30 (you should've picked Victoria rail station). Indeed the Single Fare finder refused to tell me the cost of a tube journey from Chalfont & Latimer to Baker Street, because the underlying database only contains Chalfont & Latimer Rail Station and not Chalfont & Latimer Underground Station. I think this proves it's harder to proof a database than a printed sheet of paper.
Stations outside Greater London but accessible by Oyster (by county)
Watford Junction; Broxbourne, Rye House, St Margarets, Ware, Hertford East
Merstham, Redhill, Earlswood, Salfords, Horley, Gatwick Airport (W Sussex)
Radlett, St Albans, Harpenden, Luton Airport (Beds); Potters Bar, Brookmans Park, Welham Green, Hatfield, Welwyn Garden City; Cuffley, Bayford, Hertford North
Kempton Park, Sunbury, Upper Halliford, Shepperton; Reigate
• Essex has all the luck, with its cheaply-zoned Central line stations and four c2c stations (the latter, yes, technically in Thurrock).
• The southern edge of Hertfordshire is also doing well, almost like it's part of London already. One of the next waves of Oyster extension, whenever, will see even more of the county contactless-enabled.
• Bucks (and Berks) don't really feature much at all (though Crossrail will help a bit).
• The northern strip of Surrey does well, but a lot of the county still completely misses out. Oh how the people of Epsom yearn to be part of Oyster, but there's no sign as yet (and they'll probably be beaten by the minor spur to Shepperton). As for the latest extension south, Gatwick Airport is even in West Sussex, for heaven's sake.
• It's expected that Swanley will join Dartford later in the year, but essentially Kent is electronically bereft because Southeastern are a bit rubbish, sorry.