So, there’s this shiny new extension to the Northern Line serving Nine Elms and Battersea Power Station which opened this morning. Both stations are in zone 1 so ordinarily you’d expect that the cheapest fare would be £2.40 for an adult. It probably should be, but I’ve checked out a flaw in the fares data and you can actually ride the extension for £1.50 off-peak.
It’s a little complicated, but here’s what you have to do. Start from any of Queens Road (Peckham), Peckham Rye, Denmark Hill or Wandsworth Road. NB. It doesn’t work from Clapham High Street. Travel to Clapham Junction using the London Overground. Change onto either a South Western Railway service to Queenstown Road or a Southern Railway service to Battersea Park. Exit there and walk to Battersea Power Station then take the Northern line to either Kennington or Elephant & Castle.
When you use contactless you will get a journey like the picture* (right or above). It will work either way as long as you complete all the steps. Sadly it won’t work so well using Oyster. There’s a small saving going to Kennington or Elephant & Castle, but nothing if you go back the same way.
There’s a chance this might get fixed at some point, but I’d say it has limited real world use as it’s quite a roundabout journey.
For the curious, the reason it works is that the default fare for all those combinations assumes changing between Clapham High Street and Clapham North. There is no fare defined using either the OSIs at Battersea Park or Queenstown Road so the system ignores that change and charges the default instead. With Oyster the system deducts a zone 2 National Rail journey when you exit at Queenstown Road or Battersea Park, and this higher fare (£2.30) is not reduced when ending the journey at Kennington or Elephant & Castle. In reverse it deducts a zone 1 single of £2.40 when exiting at Battersea Power Station, hence no saving at all.
*The picture has been edited now that full history is available.